diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d6c2ec0..4626fc93 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 <h2>Version 3.6.0 - ??/??/2025</h2>
       <ul>
+        <li>Now it's possibile to define custom data placeholders to be used in custom prompts [<a href="https://github.com/micz/ThunderAI/issues/156">#156</a>].</li>
         <li>When replying, it's now possibile to choose a different reply type (between "all" or "sender only") directly in the AI chat window [<a href="https://github.com/micz/ThunderAI/issues/372">#372</a>].</li>
         <li><i>[All APIs]</i> Added an option to choose to exclude a tag only with an exact match in the excluded words list [<a href="https://github.com/micz/ThunderAI/issues/395">#395</a>].</li>
         <li><i>[OpenAI API]</i> Added an option to enable the OpenAI storage for API requests [<a href="https://github.com/micz/ThunderAI/issues/406">#406</a>].</li>
diff --git a/_locales/cs/messages.json b/_locales/cs/messages.json
index 0291cc1d..a09cbf60 100644
--- a/_locales/cs/messages.json
+++ b/_locales/cs/messages.json
@@ -41,7 +41,7 @@
     "prompt_this": {
         "message": "Zeptat se"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Další informace"
     },
     "customPrompts_start_saving": {
@@ -80,13 +80,13 @@
     "customPrompts_form_label_enabled": {
         "message": "Povoleno"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Uložit vše"
     },
     "customPrompts_do_reply": {
         "message": "Odpovědět"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Přidat nový"
     },
     "customPrompts_close_button": {
diff --git a/_locales/de/messages.json b/_locales/de/messages.json
index 57c1e44f..8a4f5927 100644
--- a/_locales/de/messages.json
+++ b/_locales/de/messages.json
@@ -39,7 +39,7 @@
     "customPrompts_managePrompts": {
         "message": "Eingabeaufforderungen verwalten"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Informationen"
     },
     "customPrompts_managePrompts_info_default": {
@@ -120,10 +120,10 @@
     "customPrompts_unsaved_changes": {
         "message": "Es gibt ungespeicherte Änderungen!"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Alle speichern"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Neu hinzufügen"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/_locales/en/messages.json b/_locales/en/messages.json
index 1f1cfb1e..00f439b0 100644
--- a/_locales/en/messages.json
+++ b/_locales/en/messages.json
@@ -51,7 +51,7 @@
     "message": "Manage Prompts",
     "description": ""
   },
-  "customPrompts_managePrompts_help": {
+  "more_info_string": {
     "message": "More info",
     "description": ""
   },
@@ -167,11 +167,11 @@
     "message": "There are unsaved changes!",
     "description": ""
   },
-  "customPrompts_btnSaveAll": {
+  "btnSaveAll_string": {
     "message": "Save All",
     "description": ""
   },
-  "customPrompts_btnNew": {
+  "btnNew_string": {
     "message": "Add New",
     "description": ""
   },
@@ -315,6 +315,10 @@
     "message": "Manage your prompts",
     "description": ""
   },
+  "prefs_OptionText_btnManageCustomDataPH": {
+    "message": "Manage your data placeholders",
+    "description": ""
+  },
   "prefsInfoTitle": {
     "message": "Important Information",
     "description": ""
@@ -1555,5 +1559,61 @@
   "prefs_OptionText_add_tags_exclusions_exact_match_Info": {
     "message": "If checked, the tags in the exclusion list will be matched exactly, otherwise they will be matched partially.",
     "description": ""
+  },
+  "customDataPH_manageDataPH": {
+    "message": "Manage Data Placeholders",
+    "description": ""
+  },
+  "customDataPH_manageDataPH_info_default": {
+    "message": "You can import and export the custom data placeholders. Existing data placeholders with the same ID will be overwritten. Placeholders with new IDs will be added.",
+    "description": ""
+  },
+  "customDataPH_ExportAll": {
+    "message": "Export all custom data placeholders",
+    "description": ""
+  },
+  "customDataPH_Import": {
+    "message": "Import new data placeholders",
+    "description": ""
+  },
+  "customDataPH_form_label_Text": {
+    "message": "Data Placeholder Text",
+    "description": ""
+  },
+  "customDataPH_saving_custom": {
+    "message": "Saving custom data placeholders...",
+    "description": ""
+  },
+  "customDataPH_saved": {
+    "message": "Custom data placeholders saved!",
+    "description": ""
+  },
+  "customDataPH_btnAddNewCommit": {
+    "message": "Add the Data Placeholder",
+    "description": ""
+  },
+  "importCustomDataPH_confirmText": {
+    "message": "You are about to import new custom data placeholders.",
+    "description": ""
+  },
+  "importCustomDataPH_start_import": {
+    "message": "Starting custom data placeholders import...",
+    "description": ""
+  },
+  "importCustomDataPH_import_completed": {
+    "message": "Custom data placeholders import completed! You need to click on the 'Save All' button to save your changes.",
+    "description": ""
+  },
+  "importCustomDataPH_invalidFile": {
+    "message": "The file you're trying to import is not a valid custom data placeholders file.",
+    "description": ""
+  },
+  "importCustomDataPH_invalidDataPHs": {
+    "message": "The file you're trying to import does not contain any valid custom data placeholders.",
+    "description": ""
+  },
+  "customDataPH_add_to_menu": {
+    "message": "Usable in prompts added to menu",
+    "description": ""
   }
 }
\ No newline at end of file
diff --git a/_locales/eo/messages.json b/_locales/eo/messages.json
index 6ddc1ce7..4624c571 100644
--- a/_locales/eo/messages.json
+++ b/_locales/eo/messages.json
@@ -8,7 +8,7 @@
     "prompt_rewrite_formal": {
         "message": "Reverki formale"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Pliaj informoj"
     },
     "customPrompts_managePrompts": {
@@ -20,10 +20,10 @@
     "customPrompts_form_required_fields": {
         "message": "Postulataj kampoj"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Konservi ĉion"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Aldoni novan"
     },
     "chatgpt_btn_retry": {
diff --git a/_locales/fr/messages.json b/_locales/fr/messages.json
index 6484d226..eb2517e4 100644
--- a/_locales/fr/messages.json
+++ b/_locales/fr/messages.json
@@ -39,7 +39,7 @@
     "customPrompts_managePrompts": {
         "message": "Gérer les prompts"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Informations"
     },
     "customPrompts_managePrompts_info_default": {
@@ -120,10 +120,10 @@
     "customPrompts_unsaved_changes": {
         "message": "Il y a des modifications non enregistrées !"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Tout enregistrer"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Ajouter nouveau"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/_locales/hr/messages.json b/_locales/hr/messages.json
index 1b3c3536..4fae5f20 100644
--- a/_locales/hr/messages.json
+++ b/_locales/hr/messages.json
@@ -39,7 +39,7 @@
     "customPrompts_managePrompts": {
         "message": "Upravljaj upitima"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Više informacija"
     },
     "customPrompts_managePrompts_info_default": {
@@ -120,10 +120,10 @@
     "customPrompts_unsaved_changes": {
         "message": "Ima nespremljenih promjena!"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Spremi sve"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Dodaj novo"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/_locales/it/messages.json b/_locales/it/messages.json
index ab5c7dc4..84386a6d 100644
--- a/_locales/it/messages.json
+++ b/_locales/it/messages.json
@@ -39,7 +39,7 @@
     "customPrompts_managePrompts": {
         "message": "Gestisci i prompt"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Informazioni"
     },
     "customPrompts_managePrompts_info_default": {
@@ -120,10 +120,10 @@
     "customPrompts_unsaved_changes": {
         "message": "Ci sono modifiche non salvate!"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Salva Tutto"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Aggiungi Nuovo"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/_locales/pl/messages.json b/_locales/pl/messages.json
index 9f34bd7b..6443d310 100644
--- a/_locales/pl/messages.json
+++ b/_locales/pl/messages.json
@@ -39,7 +39,7 @@
     "customPrompts_managePrompts": {
         "message": "Zarządzaj poleceniami"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Więcej informacji"
     },
     "customPrompts_managePrompts_info_default": {
@@ -120,10 +120,10 @@
     "customPrompts_unsaved_changes": {
         "message": "Istnieją niezapisane zmiany!"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Zapisz wszystko"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Dodaj nowe"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/_locales/pt-br/messages.json b/_locales/pt-br/messages.json
index 554e1246..f6a94f1a 100644
--- a/_locales/pt-br/messages.json
+++ b/_locales/pt-br/messages.json
@@ -39,7 +39,7 @@
     "customPrompts_managePrompts": {
         "message": "Gerenciar Prompts"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Mais informações"
     },
     "customPrompts_managePrompts_info_default": {
@@ -120,10 +120,10 @@
     "customPrompts_unsaved_changes": {
         "message": "Existem alterações não salvas!"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Salvar Tudo"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Adicionar Novo"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/_locales/ru/messages.json b/_locales/ru/messages.json
index 4f1be5f7..6ad482be 100644
--- a/_locales/ru/messages.json
+++ b/_locales/ru/messages.json
@@ -26,7 +26,7 @@
     "ChatGPT_Models_Fetch": {
         "message": "Обновить список моделей ChatGPT"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "Дополнительная информация"
     },
     "customPrompts_btnEdit": {
@@ -110,10 +110,10 @@
     "customPrompts_btnDelete_confirmText": {
         "message": "Вы уверены, что хотите удалить этот элемент?"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "Сохранить все"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "Добавить новый"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/_locales/zh_Hans/messages.json b/_locales/zh_Hans/messages.json
index 6b23f5d7..33fa33d0 100644
--- a/_locales/zh_Hans/messages.json
+++ b/_locales/zh_Hans/messages.json
@@ -38,13 +38,13 @@
     "customPrompts_form_label_need_signature": {
         "message": "始终添加签名"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "新增"
     },
     "chatgpt_win_job_completed": {
         "message": "完成了！"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "保存所有变动"
     },
     "extensionDescription": {
@@ -65,7 +65,7 @@
     "customPrompts_managePrompts": {
         "message": "管理提示词"
     },
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "更多信息"
     },
     "customPrompts_managePrompts_info_default": {
diff --git a/_locales/zh_Hant/messages.json b/_locales/zh_Hant/messages.json
index b898f350..4741f617 100644
--- a/_locales/zh_Hant/messages.json
+++ b/_locales/zh_Hant/messages.json
@@ -1,5 +1,5 @@
 {
-    "customPrompts_managePrompts_help": {
+    "more_info_string": {
         "message": "更多資訊"
     },
     "prompt_reply_advanced": {
@@ -113,10 +113,10 @@
     "customPrompts_unsaved_changes": {
         "message": "有未儲存的變動！"
     },
-    "customPrompts_btnSaveAll": {
+    "btnSaveAll_string": {
         "message": "儲存全部"
     },
-    "customPrompts_btnNew": {
+    "btnNew_string": {
         "message": "新增"
     },
     "customPrompts_btnAddNewCommit": {
diff --git a/js/mzta-placeholders.js b/js/mzta-placeholders.js
index c89dd813..f640e114 100644
--- a/js/mzta-placeholders.js
+++ b/js/mzta-placeholders.js
@@ -41,6 +41,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'mail_html_body',
@@ -48,6 +49,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'mail_typed_text',
@@ -55,6 +57,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 2,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'mail_quoted_text',
@@ -62,6 +65,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 2,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'mail_subject',
@@ -69,6 +73,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'mail_folder_name',
@@ -76,6 +81,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 1,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'mail_folder_path',
@@ -83,6 +89,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 1,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'selected_text',
@@ -90,6 +97,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'selected_html',
@@ -97,6 +105,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'additional_text',
@@ -104,6 +113,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'junk_score',
@@ -111,6 +121,7 @@ const defaultPlaceholders = [
         default_value: "0",
         type: 1,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'recipients',
@@ -118,6 +129,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'cc_list',
@@ -125,6 +137,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'author',
@@ -132,6 +145,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'mail_datetime',
@@ -139,6 +153,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 1,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'current_datetime',
@@ -146,6 +161,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'account_email_address',
@@ -153,6 +169,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'tags_current_email',
@@ -160,6 +177,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'tags_full_list',
@@ -167,6 +185,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'thunderai_def_sign',
@@ -174,6 +193,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'thunderai_def_lang',
@@ -181,6 +201,7 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
     {
         id: 'empty',
@@ -188,12 +209,13 @@ const defaultPlaceholders = [
         default_value: "",
         type: 0,
         is_default: "1",
+        enabled: 1,
     },
 ];
 
 
 export async function getPlaceholders(onlyEnabled = false){
-    const _defaultPlaceholders = await getDefaultPlaceholders_withProps();
+    const _defaultPlaceholders = await getDefaultPlaceholders();
     // console.log('>>>>>>>>>>>> getPlaceholders _defaultPlaceholders: ' + JSON.stringify(_defaultPlaceholders));
     const customPlaceholders = await getCustomPlaceholders();
     // console.log('>>>>>>>>>>>> getPlaceholders customPlaceholders: ' + JSON.stringify(customPlaceholders));
@@ -207,32 +229,14 @@ export async function getPlaceholders(onlyEnabled = false){
     return output;
 }
 
-async function getDefaultPlaceholders_withProps() {
-    let prefs = await browser.storage.local.get({_default_placeholders_properties: null});
-    // console.log('>>>>>>>>>>>> getDefaultPlaceholders_withProps prefs: ' + JSON.stringify(prefs));
-    //let defaultPlaceholders_prop = [...defaultPlaceholders];
+async function getDefaultPlaceholders() {
     let defaultPlaceholders_prop = JSON.parse(JSON.stringify(defaultPlaceholders));
     // console.log('>>>>>>>>>>>> getDefaultPlaceholders_withProps defaultPlaceholders: ' + JSON.stringify(defaultPlaceholders));
     // console.log('>>>>>>>>>>>> getDefaultPlaceholders_withProps defaultPlaceholders_prop: ' + JSON.stringify(defaultPlaceholders_prop));
-    if(prefs._default_placeholders_properties === null){     // no default Placeholders properties saved
-        defaultPlaceholders_prop.forEach((placeholder) => {
-            placeholder.enabled = 1;
-        })
-        // console.log('>>>>>>>>>>>> getDefaultPlaceholders_withProps [no prop saved] defaultPlaceholders_prop: ' + JSON.stringify(defaultPlaceholders_prop));
-    } else {    // we have saved default Placeholders properties
-        defaultPlaceholders_prop.forEach((placeholder) => {
-            if(prefs._default_Placeholders_properties?.[placeholder.id]){
-                placeholder.enabled = prefs._default_Placeholders_properties[placeholder.id].enabled;
-            }else{
-                placeholder.enabled = 1;
-            }
-        })
-        // console.log('>>>>>>>>>>>> getDefaultPlaceholders_withProps [prop saved] defaultPlaceholders_prop: ' + JSON.stringify(defaultPlaceholders_prop));
-    }
     return defaultPlaceholders_prop;
 }
 
-async function getCustomPlaceholders() {
+export async function getCustomPlaceholders() {
     let prefs = await browser.storage.local.get({_custom_placeholder: null});
     if(prefs._custom_placeholder === null){
         return [];
@@ -241,22 +245,61 @@ async function getCustomPlaceholders() {
     }
 }
 
-export async function setDefaultPlaceholdersProperties(placeholders) {
-    let default_placeholders_properties = {};
-    placeholders.forEach((placeholder) => {
-        default_placeholders_properties[placeholder.id] = {enabled: placeholder.enabled};
+export async function setCustomPlaceholders(placeholders) {
+    placeholders.forEach(ph => {
+        ph.id = placeholdersUtils.validateCustomDataPH_ID(ph.id);
+        ph.is_default = "0";
     });
-    //console.log('>>>>>>>>>>>>>> default_placeholders_properties: ' + JSON.stringify(default_placeholders_properties));
-    await browser.storage.local.set({_default_placeholders_properties: default_placeholders_properties});
+    await browser.storage.local.set({_custom_placeholder: placeholders});
 }
 
-export async function setCustomPlaceholders(placeholders) {
-    await browser.storage.local.set({_custom_placeholder: placeholders});
+export function prepareCustomDataPHsForExport(placeholders){
+    let output = [...placeholders];
+    output.forEach(placeholder => {
+        if(placeholder.is_default == 0){
+            delete placeholder['idnum'];
+        }
+    });
+    return output;
+}
+
+export async function prepareCustomDataPHsForImport(placeholders){
+    // console.log(">>>>>>>>>>> prepareCustomDataPHsForImport prompts: " + JSON.stringify(prompts));
+    const output = await getCustomPlaceholders();
+    // console.log(">>>>>>>>>>> prepareCustomDataPHsForImport output: " + JSON.stringify(output));
+    placeholders.forEach(placeholder => {
+        if(output.some(p => p.id == placeholder.id)){
+            Object.keys(placeholder).forEach(key => {
+               output.find(p => p.id == placeholder.id)[key] = placeholder[key];
+            })
+        }else{
+            output.push(placeholder);
+        }
+    });
+    output.sort((a, b) => a.id.localeCompare(b.id));
+    // console.log(">>>>>>>>>>> prepareCustomDataPHsForImport final output: " + JSON.stringify(output));
+    return output;
 }
 
 
 export const placeholdersUtils = {
 
+    customPrefix: 'thunderai_custom_',
+
+    validateCustomDataPH_ID(placeholder_id){
+        if (!placeholder_id.startsWith(this.customPrefix)) {
+            return this.customPrefix + placeholder_id;
+        }
+        return placeholder_id;
+    },
+
+    stripCustomDataPH_ID_Prefix(placeholder_id){
+        if (placeholder_id.startsWith(this.customPrefix)) {
+            return placeholder_id.substring(this.customPrefix.length);
+        }
+        return placeholder_id;
+    },
+
     async extractPlaceholders(text) {
         // Regular expression to match patterns like {%...%}
         const regex = /{%\s*(.*?)\s*%}/g;
@@ -292,6 +335,19 @@ export const placeholdersUtils = {
         });
     },
 
+    async replaceCustomPlaceholders(text) {
+        let customPlaceholders = await getCustomPlaceholders(true);
+        // Regular expression to match patterns like {%thunderai_custom_...%}
+        return text.replace(/{%\s*thunderai_custom_(.*?)\s*%}/g, function(match, p1) {
+          // p1 contains the key inside {% %}
+          const currPlaceholder = customPlaceholders.find(ph => ph.id === 'thunderai_custom_' + p1);
+          if (!currPlaceholder) {
+            return match;
+          }
+          return currPlaceholder.text;
+        });
+    },
+
     hasPlaceholder(text, placeholder = "") {
         let regex;
       
@@ -306,9 +362,30 @@ export const placeholdersUtils = {
       
         // Check if the specific or any placeholder is present in the text
         return regex.test(text);
-      },
+    },
+
+    hasCustomPlaceholder(text, placeholder = "") {
+        let regex;
+      
+        // If a specific placeholder is provided, we search for it
+        if (placeholder !== "") {
+          // Dynamically build the regex for the specific placeholder
+          regex = new RegExp(`{%\s*${placeholder}\s*%}`);
+        } else {
+          // Otherwise, we search for any placeholder in the format {%thunderai_custom_ ... %}
+          regex = /{%\s*thunderai_custom_(.*?)\s*%}/;
+        }
+      
+        // Check if the specific or any placeholder is present in the text
+        return regex.test(text);
+    },
 
     async getPlaceholdersValues(prompt_text, curr_message, mail_subject, body_text, msg_text, only_typed_text, only_quoted_text, selection_text, selection_html, tags_full_list) {
+        // check if we have custom placeholders
+        if(placeholdersUtils.hasCustomPlaceholder(prompt_text)){
+            prompt_text = await placeholdersUtils.replaceCustomPlaceholders(prompt_text);
+        }
+
         let currPHs = await placeholdersUtils.extractPlaceholders(prompt_text);
         // console.log(">>>>>>>>>> currPHs: " + JSON.stringify(currPHs));
         let finalSubs = {};
diff --git a/js/mzta-utils.js b/js/mzta-utils.js
index b044d2db..b8d1b4ac 100644
--- a/js/mzta-utils.js
+++ b/js/mzta-utils.js
@@ -587,7 +587,7 @@ const insertHtml = function (replyHtml, fullBody_string) {
   return fullBody.body.innerHTML;
 }
 
-export async function getCustomPromptsUsedSpace(){
+export async function getLocalStorageUsedSpace(){
   // we can't use this, see: https://bugzilla.mozilla.org/show_bug.cgi?id=1385832
   //let customprompts_space = await browser.storage.local.getBytesInUse("_custom_prompt");
   //let's use a workaround
diff --git a/options/mzta-options.html b/options/mzta-options.html
index 7cde8e5a..7796cad0 100644
--- a/options/mzta-options.html
+++ b/options/mzta-options.html
@@ -12,7 +12,7 @@
         <td colspan="2"><div>__MSG_prefs_SurveyLinkText__<br><a href="https://forms.gle/1qK2wcbuhaRzhwyt9">__MSG_prefs_SurveyLinkText2__</a></div></td>
       </tr>
       <tr id="owl_warning">
-        <td colspan="2"><div class="warning">__MSG_prefs_OptionText_owl_warning__ <a href="https://micz.it/thunderbird-addon-thunderai/owl/">__MSG_customPrompts_managePrompts_help__</a></div></td>
+        <td colspan="2"><div class="warning">__MSG_prefs_OptionText_owl_warning__ <a href="https://micz.it/thunderbird-addon-thunderai/owl/">__MSG_more_info_string__</a></div></td>
       </tr>
       <tr id="hyprland_warning">
         <td colspan="2" style="text-align:center;" class="warning"><b>__MSG_hyprland_warning__</b></td>
@@ -297,7 +297,7 @@
       </tr>
       <tr class="conntype_ollama_api" id="ollama_api_cors_warning">
         <td colspan="2" style="text-align:center;">
-          __MSG_remember_CORS__ [<a href="https://micz.it/thunderbird-addon-thunderai/ollama-cors-information/">__MSG_customPrompts_managePrompts_help__</a>]
+          __MSG_remember_CORS__ [<a href="https://micz.it/thunderbird-addon-thunderai/ollama-cors-information/">__MSG_more_info_string__</a>]
           <br><br><b>__MSG_CORS_alternative_1__</b>
           <br>__MSG_CORS_alternative_2__
             <br><br><button id="btnGiveAllUrlsPermission_ollama_api">__MSG_CORS_give_allurls_perm__</button>
@@ -365,7 +365,7 @@
       </tr>
       <tr class="conntype_openai_comp_api" id="openai_comp_api_cors_warning">
         <td colspan="2" style="text-align:center;">
-          __MSG_maybe_CORS_openai_comp__ [<a href="https://micz.it/thunderbird-addon-thunderai/ollama-cors-information/">__MSG_customPrompts_managePrompts_help__</a>]
+          __MSG_maybe_CORS_openai_comp__ [<a href="https://micz.it/thunderbird-addon-thunderai/ollama-cors-information/">__MSG_more_info_string__</a>]
           <br><br><b>__MSG_CORS_alternative_1__</b>
           <br>__MSG_CORS_alternative_2__
             <br><br><button id="btnGiveAllUrlsPermission_openai_comp_api">__MSG_CORS_give_allurls_perm__</button>
@@ -542,14 +542,15 @@
     </table>
     <div id="btn_custom_prompts">
         <button id="btnManagePrompts">__MSG_prefs_OptionText_btnManagePrompts__</button>
-        <br>__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_customPrompts_managePrompts_help__</a>
+        <br>__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_more_info_string__</a>
+        <br><button id="btnManageCustomDataPH">__MSG_prefs_OptionText_btnManageCustomDataPH__</button>
     </div>
     <div id="miczDescription">
       <h1>__MSG_prefsInfoTitle__</h1>
       <p>
         <span class="conntype_chatgpt_web">__MSG_prefsInfoDesc_1__<br></span>
         <span class="conntype_chatgpt_api">__MSG_prefsInfoDesc_2__<br></span>
-        <span class="conntype_ollama_api">__MSG_prefsInfoDesc_3__ [<a href="https://micz.it/thunderbird-addon-thunderai/ollama-cors-information/">__MSG_customPrompts_managePrompts_help__</a>]<br></span>
+        <span class="conntype_ollama_api">__MSG_prefsInfoDesc_3__ [<a href="https://micz.it/thunderbird-addon-thunderai/ollama-cors-information/">__MSG_more_info_string__</a>]<br></span>
         <span class="conntype_openai_comp_api">__MSG_prefsInfoDesc_4__</span>
         <br><span>__MSG_prefsInfoDesc_5__
           <br>__MSG_prefsInfoDesc_6__</span>
diff --git a/options/mzta-options.js b/options/mzta-options.js
index 9828e054..85e842d2 100644
--- a/options/mzta-options.js
+++ b/options/mzta-options.js
@@ -482,6 +482,10 @@ document.addEventListener('DOMContentLoaded', async () => {
     openTab('../pages/customprompts/mzta-custom-prompts.html');
   });
 
+  document.getElementById('btnManageCustomDataPH').addEventListener('click', () => {
+    openTab('../pages/customdataplaceholders/mzta-custom-dataplaceholders.html');
+  });
+
   document.getElementById('btnManageTagsInfo').addEventListener('click', () => {
     openTab('../pages/addtags/mzta-add-tags.html');
   });
diff --git a/options/mzta-release-notes.html b/options/mzta-release-notes.html
index da606a40..ccda247d 100644
--- a/options/mzta-release-notes.html
+++ b/options/mzta-release-notes.html
@@ -9,6 +9,7 @@
     <div id="miczRelNotes"><h1>ThunderAI Release Notes</h1>
       <h2>Version 3.6.0 - ??/??/2025</h2>
       <ul>
+        <li>Now it's possibile to define custom data placeholders to be used in custom prompts [<a href="https://github.com/micz/ThunderAI/issues/156">#156</a>].</li>
         <li>When replying, it's now possibile to choose a different reply type (between "all" or "sender only") directly in the AI chat window [<a href="https://github.com/micz/ThunderAI/issues/372">#372</a>].</li>
         <li><i>[All APIs]</i> Added an option to choose to exclude a tag only with an exact match in the excluded words list [<a href="https://github.com/micz/ThunderAI/issues/395">#395</a>].</li>
         <li><i>[OpenAI API]</i> Added an option to enable the OpenAI storage for API requests [<a href="https://github.com/micz/ThunderAI/issues/406">#406</a>].</li>
diff --git a/pages/customprompts/list.js b/pages/_lib/list.js
similarity index 100%
rename from pages/customprompts/list.js
rename to pages/_lib/list.js
diff --git a/pages/addtags/mzta-add-tags.html b/pages/addtags/mzta-add-tags.html
index 593116b7..ef5d2488 100644
--- a/pages/addtags/mzta-add-tags.html
+++ b/pages/addtags/mzta-add-tags.html
@@ -98,7 +98,7 @@
     </table>
     <div id="addtags_prompt_container">
         <span class="section_title">__MSG_AddTags_prompt_text_title__</span><span id="addtags_prompt_unsaved" class="unsaved hidden"> __MSG_customPrompts_unsaved_changes__</span>
-        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_customPrompts_managePrompts_help__</a>
+        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_more_info_string__</a>
           <br>__MSG_prefs_OptionText_btnManagePrompts_infoline3__
           <br><b>__MSG_prefs_OptionText_AdvancedPromptResponse_infoline2__</b></span>
         <br>
diff --git a/pages/customdataplaceholders/mzta-custom-dataplaceholders.css b/pages/customdataplaceholders/mzta-custom-dataplaceholders.css
new file mode 100644
index 00000000..888459df
--- /dev/null
+++ b/pages/customdataplaceholders/mzta-custom-dataplaceholders.css
@@ -0,0 +1,360 @@
+@media (prefers-color-scheme: light) {
+    table th {
+        background-color: #ffffff;
+    }
+
+    #command_palette{
+        background-color: #ffffff; 
+    }
+
+    table.prompts_list tr:nth-child(even) {
+        background-color: #e9e9e9;
+    }
+
+    table.prompts_list tr:nth-child(odd) {
+        background-color: #f3f3f3;
+    }
+}
+
+table {
+    border-collapse: collapse;
+    border-spacing: 0;
+    border: 1px solid #ccc;
+}
+
+thead {
+    position: sticky;
+    top: 26px;
+    z-index: 90;
+}
+
+#command_palette{
+    position: sticky;
+    top: 0;
+    padding-top: 1px;
+    height: 26px;
+    width: 100%;
+    z-index: 90;
+}
+
+#btnNew{
+    float: right;
+}
+
+#btnSaveAll{
+    float: left;
+}
+
+#msgDisplay{
+    padding-left: 40px;
+}
+
+table tr {
+    border-bottom: 1px solid #ccc;
+}
+
+table.prompts_list th {
+    padding: 8px;
+    text-align: left;
+}
+
+table td {
+    border: 1px solid #ddd;
+    padding: 8px;
+}
+
+table td.w08{
+    width: 8vw;
+}
+
+table td.w17{
+    width: 17vw;
+}
+
+table td.w19{
+    width: 19vw;
+}
+
+table td.w25{
+    width: 25vw;
+}
+
+table td.w40{
+    width: 40vw;
+}
+
+table.prompts_list td.properties{
+    white-space: nowrap;
+}
+
+table .sort {
+    background-image: url(../images/listjs-arrow-sort-inactive.png);
+    background-repeat: no-repeat;
+    background-position: right center;
+    padding-right: 14px;
+    cursor: pointer;
+    cursor: hand;
+}
+
+table .sort.asc {
+    background-image: url(../images/listjs-arrow-sort-active-down.png);
+}
+
+table .sort.desc {
+    background-image: url(../images/listjs-arrow-sort-active-up.png);
+}
+
+tbody.list tr{
+    vertical-align: top;
+}
+
+.hiddendata{
+    display: none;
+}
+
+#formNew{
+    display: none;
+    width: 100%;
+    padding-bottom: 7px;
+}
+
+.text_output{
+    width: 98%;
+    height: 9em;
+}
+
+.go_right_float{
+    float: right;
+}
+
+.go_right{
+    width: 100%;
+    text-align: right;
+}
+
+.width_all{
+    width: 100%;
+}
+
+.small_label{
+    font-size: small;
+    font-style: italic;
+}
+
+.field_title{
+    font-weight: bold;
+}
+
+.field_title_s{
+    font-weight: bold;
+    font-size: small;
+}
+
+.field_title_us{
+    font-weight: bold;
+    font-size: smaller;
+}
+
+label, .id_show, .text_show, .name_show, .type_show, .action_show{
+    font-size: small;
+}
+
+#txtIdNew, .id_output{
+    text-transform: lowercase;
+}
+
+#import_export{
+    position: absolute;
+    right:10px;
+    top:10px;
+    text-align: right;
+}
+
+#btnExportAll{
+    margin-bottom: 3px;
+}
+
+.storage_space{
+    font-size: 0.8em;
+    font-weight: normal;
+    font-style: italic;
+    color: rgb(41, 41, 41);
+    text-align: right;
+    margin-right: 1px;
+}
+
+.page_title{
+    margin-bottom: 0px;
+}
+
+.autocomplete-container {
+    position: relative;
+}
+
+.autocomplete-list {
+    position: absolute;
+    top: 100%;
+    left: 0;
+    right: 0;
+    background-color: white;
+    border: 1px solid #ccc;
+    z-index: 1000;
+    max-height: 200px;
+    overflow-y: auto;
+    padding: 0;
+    margin: 0;
+    list-style: none;
+    font-size: small;
+}
+
+.autocomplete-list li {
+    padding: 8px;
+    cursor: pointer;
+}
+
+.autocomplete-list li:hover {
+    background-color: #f0f0f0;
+}
+
+.autocomplete-list li.active {
+    background-color: #ddd;
+}
+
+.hidden {
+    display: none;
+}
+
+.need_custom_text_span, .need_selected_span{
+    padding-right: 2px;
+}
+
+#chatgpt_web_additional_info_toggle td{
+    padding:0px 5px;
+    font-style: italic;
+}
+
+#chatgpt_web_additional_info, #chatgpt_web_additional_info_toggle, .chatgpt_web_additional_info, .chatgpt_web_additional_info_toggle, .chatgpt_web_additional_info_show{
+    background-color: rgb(255, 209, 183);
+    display:none;
+}
+
+.chatgpt_web_models_list_table{
+    background-color: rgb(255, 209, 183);
+    border:0;
+}
+
+.chatgpt_web_models_list_table *{
+    border:0;
+}
+
+.chatgpt_web_models_list_table td{
+    padding:2px;
+}
+
+#chatgpt_web_additional_info_toggle, .chatgpt_web_additional_info_toggle{
+    cursor: pointer;
+}
+
+#chatgpt_web_additional_info_toggle:hover, .chatgpt_web_additional_info_toggle:hover{
+    background-color: rgb(255, 189, 153);
+    text-decoration: underline;
+}
+
+#chatgpt_web_additional_info_toggle td{
+    text-align: center;
+}
+
+#chatgpt_web_additional_info td{
+    vertical-align: top;
+}
+
+.chatgpt_web_additional_info_toggle{
+    width: -moz-available;
+    text-align: center;
+    margin-top: 10px;
+}
+
+.chatgpt_web_additional_info_show{
+    flex-direction: column;
+    justify-content: space-between;
+    height: 100%;
+    padding: 3px;
+    margin-top: 5px;
+}
+
+.chatgpt_web_additional_info_row{
+    display: flex;
+}
+
+.chatgpt_web_additional_info_row span{
+    margin-right: 0.4em;
+}
+
+input.input_additional[type="text"]{
+    width: -moz-available;
+}
+
+.small_info{
+    font-size:smaller;
+}
+
+.conntype_chatgpt_web_option{
+    cursor: pointer;
+}
+
+@media (prefers-color-scheme: dark) {
+    body {
+        background-color: #1C1B22;
+        color: rgb(251, 251, 254);
+    }
+    
+    a:link { color: #409EFF; }   
+    a:visited { color: #409EFF; }  
+    a:hover { color: #66B1FF; }   
+    a:active { color: #66B1FF; }
+
+    table {
+        background-color: #1C1B22;
+        border: 1px solid #ccc;
+    }
+
+    table.prompts_list th {
+        background-color: #4c4e58;
+        border: 1px solid rgb(251, 251, 254);
+        color: rgb(194, 194, 194);
+    }
+
+    #command_palette{
+        background-color: inherit; 
+    }
+
+    table.prompts_list tr:nth-child(even) {
+        background-color: #2E2F36;
+    }
+
+    .storage_space{
+        color: rgb(182, 182, 182);
+    }
+
+    .autocomplete-list {
+        background-color: #2E2F36;
+        border: 1px solid #2E2F36;
+    }
+    
+    .autocomplete-list li:hover {
+        background-color: #4c4e58;
+    }
+    
+    .autocomplete-list li.active {
+        background-color: #4c4e58;
+    }
+
+    #chatgpt_web_additional_info, #chatgpt_web_additional_info_toggle, .chatgpt_web_additional_info, .chatgpt_web_additional_info_toggle, .chatgpt_web_additional_info_show, .chatgpt_web_models_list_table{
+        background-color: rgb(39, 11, 0);
+        color: rgb(182, 182, 182);
+    }
+
+    #chatgpt_web_additional_info_toggle:hover, .chatgpt_web_additional_info_toggle:hover{
+        background-color: rgb(88, 25, 0);
+    }
+}
\ No newline at end of file
diff --git a/pages/customdataplaceholders/mzta-custom-dataplaceholders.html b/pages/customdataplaceholders/mzta-custom-dataplaceholders.html
new file mode 100644
index 00000000..86a4263d
--- /dev/null
+++ b/pages/customdataplaceholders/mzta-custom-dataplaceholders.html
@@ -0,0 +1,84 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="UTF-8">
+    <title>ThunderAI - __MSG_customDataPH_manageDataPH__</title>
+    <link rel="stylesheet" href="mzta-custom-dataplaceholders.css">
+    <link rel="icon" href="../../images/icon-16px.png">
+</head>
+<body>
+    <div>
+        <h1 class="page_title">__MSG_customDataPH_manageDataPH__</h1>
+        <p>__MSG_customDataPH_manageDataPH_info_default__<br>
+            __MSG_customPrompts_managePrompts_info_default_3__
+        <br>__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_more_info_string__</a></p>
+    </div>
+    <div id="import_export">
+        <button id="btnExportAll">__MSG_customDataPH_ExportAll__</button><br>
+        <button id="btnImport">__MSG_customDataPH_Import__</button>
+    </div>
+    <div id="command_palette">
+      <button id="btnSaveAll" disabled>__MSG_btnSaveAll_string__</button>
+      <span id="msgDisplay"></span>
+      <button id="btnNew">__MSG_btnNew_string__</button>
+    </div>
+    <div id="formNew">
+      <table class="width_all">
+        <tr>
+            <td class="w19">
+                <label for="txtIdNew" class="field_title">*__MSG_customPrompts_form_label_ID__:</label>
+                <br>
+                <i>thunderai_custom_</i><input type="text" id="txtIdNew" name="id" class="input_new" tabindex="1">
+                <br><span class="small_label">[__MSG_customPrompts_form_label_ID_rules__]</span>                
+            </td>
+            <td rowspan="2" class="w25">
+                <label for="txtTextNew" class="field_title">*__MSG_customDataPH_form_label_Text__:</label>
+                <br>
+                <div class="autocomplete-container">
+                    <textarea id="txtTextNew" name="text" class="input_new text_output editor" tabindex="3"></textarea>
+                    <ul class="autocomplete-list hidden"></ul>
+                </div>
+            </td>
+			<td rowspan="2" class="w19">
+                <label for="selectTypeNew" class="field_title">__MSG_customDataPH_add_to_menu__:</label>
+                <br>
+                <select id="selectTypeNew" name="type" tabindex="4" class="type_output">
+                    <option value="0">__MSG_customPrompts_add_to_menu_always__</option>
+                    <option value="1">__MSG_customPrompts_add_to_menu_reading__</option>
+                    <option value="2">__MSG_customPrompts_add_to_menu_composing__</option>
+                </select>
+            </td>
+        </tr>
+        <tr>
+            <td class="w19">
+              <label for="txtNameNew" class="field_title">*__MSG_customPrompts_form_label_Name__:</label>
+              <br>
+              <input type="text" id="txtNameNew" name="name" class="input_new" tabindex="2">
+            </td>
+        </tr>
+    </table>
+        <div class="go_right_float">* __MSG_customPrompts_form_required_fields__</div>
+        <br>
+        <div class="go_right"><button id="btnAddNew" disabled>__MSG_customDataPH_btnAddNewCommit__</button></div>
+    </div>
+    <div id="all_custom_dataplaceholders">
+        <table class="prompts_list">
+            <thead>
+              <tr>
+                <th class="sort" data-sort="id">__MSG_customPrompts_form_label_ID__</th>
+                <th class="sort" data-sort="name">__MSG_customPrompts_form_label_Name__</th>
+                <th class="sort" data-sort="text">__MSG_customDataPH_form_label_Text__</th>
+				<th>__MSG_customPrompts_Properties__</th>
+                <th>&nbsp;</th>
+              </tr>
+            </thead>
+            <tbody class="list">
+            </tbody>
+          </table>
+    </div>
+    <div class="storage_space">__MSG_StorageSpace__: <span id="storage_space"></span></div>
+    <script src="../_lib/list.js"></script>
+    <script src="mzta-custom-dataplaceholders.js" type="module"></script>
+    <script src="../../js/mzta-i18n.js"></script>
+</body>
+</html>
\ No newline at end of file
diff --git a/pages/customdataplaceholders/mzta-custom-dataplaceholders.js b/pages/customdataplaceholders/mzta-custom-dataplaceholders.js
new file mode 100644
index 00000000..d359b897
--- /dev/null
+++ b/pages/customdataplaceholders/mzta-custom-dataplaceholders.js
@@ -0,0 +1,564 @@
+/*
+ *  ThunderAI [https://micz.it/thunderbird-addon-thunderai/]
+ *  Copyright (C) 2024 - 2025  Mic (m@micz.it)
+
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import { prefs_default } from "../../options/mzta-options-default.js";
+import { getLocalStorageUsedSpace, sanitizeHtml, isThunderbird128OrGreater } from "../../js/mzta-utils.js";
+import { taLogger } from "../../js/mzta-logger.js";
+import { getPlaceholders, setCustomPlaceholders, getCustomPlaceholders, prepareCustomDataPHsForExport, prepareCustomDataPHsForImport, placeholdersUtils } from "../../js/mzta-placeholders.js";
+import { textareaAutocomplete } from "../../js/mzta-placeholders-autocomplete.js";
+
+let prefs = null;
+var customDataPHsList = null;
+var somethingChanged = false;
+var idnumMax = 0;
+var msgTimeout = null;
+let taLog = null;
+let autocompleteSuggestions = [];
+
+document.addEventListener('DOMContentLoaded', async () => {
+
+    prefs = await browser.storage.sync.get({ do_debug: prefs_default.do_debug });
+    taLog = new taLogger("mzta-custom-dataplaceholders", prefs.do_debug);
+    
+    setStorageSpace();
+    
+    let values = await getCustomPlaceholders();
+
+    //console.log('>>>>>>>>>>>>>>>> values: ' + JSON.stringify(values));
+
+    loadCustomDataPHsList(values);
+
+    const btnSaveAll = document.getElementById('btnSaveAll');
+    btnSaveAll.disabled = true;
+    
+    // Disable save button and handle save actions
+    function handleSaveAllClick(e) {
+        e.preventDefault();
+        saveAll();
+        clearFields();
+    }
+    btnSaveAll.addEventListener('click', handleSaveAllClick);
+
+    const btnNew = document.getElementById('btnNew');
+    
+    // Show the new item form
+    function handleNewClick(e) {
+        e.preventDefault();
+        e.target.disabled = true;
+        document.getElementById('formNew').style.display = 'block';
+        window.scrollTo({
+            top: 0,
+            behavior: 'smooth'
+        });
+    }
+    btnNew.addEventListener('click', handleNewClick);
+    
+    // for the new prompt form
+    let btnNew_elements = document.querySelectorAll(".input_new");
+    if(btnNew_elements) {
+        btnNew_elements.forEach(element => {
+            element.addEventListener('change', (e) => {
+                e.preventDefault();
+                checkFields();
+            });
+        });
+    }
+
+    const textareas = document.querySelectorAll('.editor');
+    autocompleteSuggestions = (await getPlaceholders())
+        .filter(p => p.is_default == "1")
+        .map(p => ({ command: '{%' + p.id + '%}', type: p.type }));
+
+    // console.log('>>>>>>>>>>> suggestions: ' + JSON.stringify(suggestions));
+    
+    textareas.forEach(textarea => {
+        textareaAutocomplete(textarea, autocompleteSuggestions);
+        textareas.forEach(textarea => {
+            textarea.addEventListener('input', (e) => {
+                checkPromptsConfigForPlaceholders(e.target);
+            });
+        textareaAutocomplete(textarea, autocompleteSuggestions);
+        });
+    });
+
+    i18n.updateDocument();
+
+    //To add a new item
+    var txtIdNew = document.getElementById('txtIdNew');
+    var txtNameNew = document.getElementById('txtNameNew');
+    var txtTextNew = document.getElementById('txtTextNew');
+	var selectTypeNew = document.getElementById('selectTypeNew');
+    var checkboxNeedSelectedNew = document.getElementById('checkboxNeedSelectedNew');
+    var checkboxNeedCustomTextNew = document.getElementById('checkboxNeedCustomTextNew');
+
+    const btnAddNew = document.getElementById('btnAddNew');
+    btnAddNew.addEventListener('click', (e) => {
+        e.preventDefault();
+        if(!checkFields()) {
+            return;
+        }
+        let newItemData = {
+            id: String(txtIdNew.value.trim()).toLocaleLowerCase(),
+            name: txtNameNew.value.trim(),
+            text: txtTextNew.value.trim(),
+			type: selectTypeNew.value,
+            enabled: 1,
+            is_default: 0,
+            idnum: idnumMax + 1,
+        };
+
+        let newItem = customDataPHsList.add(newItemData);
+        idnumMax++;
+        let curr_idnum = newItem[0].values().idnum;
+        let checkboxes = document.querySelectorAll(`tr[data-idnum="${curr_idnum}"] input[type="checkbox"]`);
+        checkSelectedBoxes(checkboxes);
+        let editBtn = document.querySelector(`tr[data-idnum="${curr_idnum}"] button.btnEditItem`);
+        //console.log(`>>>>>>>>>>>> tr[data-idnum="${curr_idnum}"] button.btnEditItem`);
+        editBtn.addEventListener('click', handleEditClick);
+        //console.log('>>>>>>>>>>>>> editBtn: ' + JSON.stringify(editBtn));
+        let deleteBtn = document.querySelector(`tr[data-idnum="${curr_idnum}"] button.btnDeleteItem`);
+        //console.log(`>>>>>>>>>>>> tr[data-idnum="${curr_idnum}"] button.btnDeleteItem`);
+        deleteBtn.addEventListener('click', handleDeleteClick);
+        let okBtn = document.querySelector(`tr[data-idnum="${curr_idnum}"] button.btnConfirmItem`);
+        okBtn.addEventListener('click', handleConfirmClick);
+        let cancelBtn = document.querySelector(`tr[data-idnum="${curr_idnum}"] button.btnCancelItem`);
+        cancelBtn.addEventListener('click', handleCancelClick);
+        // console.log('>>>>>>>>>>>>> deleteBtn: ' + JSON.stringify(deleteBtn));
+        // console.log('>>>>>>>>>>>>> newItem: ' + JSON.stringify(newItem));
+        document.getElementById('btnNew').disabled = false;
+        clearFields();
+        setSomethingChanged();
+        i18n.updateDocument();
+        window.scrollTo({
+            top: document.body.scrollHeight,
+            behavior: 'smooth'
+          });
+    });
+
+    //Import Export
+    const btnExportAll = document.getElementById('btnExportAll');
+    btnExportAll.addEventListener('click', (e) => {
+        e.preventDefault();
+        exportCustomDataPHs();
+    });
+
+    async function exportCustomDataPHs() {
+        const manifest = browser.runtime.getManifest();
+        const addonVersion = manifest.version;
+        const outputCustomDataPHs = prepareCustomDataPHsForExport(await getCustomPlaceholders());
+        let outputObj = {id: 'thunderai-custom-data-placeholders', addon_version: addonVersion, customdataplaceholders: outputCustomDataPHs};
+        const blob = new Blob([JSON.stringify(outputObj, null, 2)], {
+            type: "application/json",
+          });
+        const currentDate = new Date();
+        const time_stamp = `${currentDate.getFullYear()}${String(currentDate.getMonth() + 1).padStart(2, '0')}${String(currentDate.getDate()).padStart(2, '0')}${String(currentDate.getHours()).padStart(2, '0')}${String(currentDate.getMinutes()).padStart(2, '0')}${String(currentDate.getSeconds()).padStart(2, '0')}`;
+        messenger.downloads.download({
+            url: URL.createObjectURL(blob),
+            filename: `thunderai-custom-data-placeholders-${time_stamp}.json`,
+            saveAs: true,
+        });
+    }
+
+    const btnImport = document.getElementById('btnImport');
+    btnImport.addEventListener('click', (e) => {
+        e.preventDefault();
+        importCustomDataPHs();
+    });
+
+    function importCustomDataPHs() {
+        if(confirm(browser.i18n.getMessage("importCustomDataPH_confirmText") + '\n' + browser.i18n.getMessage("customDataPH_manageDataPH_info_default") + '\n' + browser.i18n.getMessage("customPrompts_managePrompts_info_default_3"))) {
+            //ask the user to choose a JSON file, and then read it, check if the serialized JSON is valid as generated from importCustomDataPHs(), and if so, add it to the list
+            const input = document.createElement('input');
+            input.type = 'file';
+            input.accept = '.json';
+            input.click();
+            input.onchange = async () => {
+                setMessage(browser.i18n.getMessage('importCustomDataPH_start_import'));
+                const file = input.files[0];
+                const reader = new FileReader();
+                reader.onload = async () => {
+                    const json = reader.result;
+                    try {
+                        const obj = JSON.parse(json);
+                        if(obj.id !== 'thunderai-custom-data-placeholders') {
+                            alert(browser.i18n.getMessage("importCustomDataPH_invalidFile"));
+                            setMessage(browser.i18n.getMessage('importCustomDataPH_invalidFile'),'red');
+                            return;
+                        }
+                        // if(obj.addon_version !== manifest.version) {
+                        //     alert(browser.i18n.getMessage("importPrompts_invalidVersion"));
+                        //     return;
+                        // }
+                        if(!Array.isArray(obj.customdataplaceholders)) {
+                            alert(browser.i18n.getMessage("importCustomDataPH_invalidDataPHs"));
+                            setMessage(browser.i18n.getMessage('importCustomDataPH_invalidDataPHs'),'red');
+                            return;
+                        }
+                        customDataPHsList.clear();
+                        loadCustomDataPHsList(await prepareCustomDataPHsForImport(obj.customdataplaceholders));
+                        setSomethingChanged();
+                        i18n.updateDocument();
+                        setMessage(browser.i18n.getMessage('importCustomDataPH_import_completed'), 'orange');
+                    } catch(err) {
+                        alert(browser.i18n.getMessage("importCustomDataPH_invalidFile") + ' ' + err);
+                        setMessage(browser.i18n.getMessage('importCustomDataPH_invalidFile'),'red');
+                        return;
+                    }
+                };
+                reader.readAsText(file);
+            };
+        };
+    }
+
+}, { once: true });
+
+//========= handling an item in a row 
+function handleEditClick(e) {
+    e.preventDefault();
+    const tr = e.target.parentNode.parentNode;
+    //console.log('>>>>>>>> tr: ' + tr.getAttribute('data-idnum'));
+    e.target.style.display = 'none';    // Edit btn
+    tr.querySelector('.btnConfirmItem').style.display = 'inline';   // Save btn
+    tr.querySelector('.btnCancelItem').style.display = 'inline';   // Cancel btn
+//        tr.querySelector('.btnEditItem').style.display = 'none';   // Edit btn
+    tr.querySelector('.btnDeleteItem').style.display = 'none';   // Delete btn
+    showItemRowEditor(tr);
+}
+
+function showItemRowEditor(tr) {
+    tr.querySelector('.id_output').style.display = 'inline';
+    tr.querySelector('.id_show').style.display = 'none';
+    tr.querySelector('.name_output').style.display = 'inline';
+    tr.querySelector('.name_show').style.display = 'none';
+    const text_output = tr.querySelector('.text_output');
+    text_output.style.display = 'inline';
+    textareaAutocomplete(text_output, autocompleteSuggestions)
+    tr.querySelector('.text_show').style.display = 'none';
+	tr.querySelector('.type_output').style.display = 'inline';
+    tr.querySelector('.type_show').style.display = 'none';
+}
+
+function hideItemRowEditor(tr) {
+    tr.querySelector('.id_output').style.display = 'none';
+    tr.querySelector('.id_show').style.display = 'inline';
+    tr.querySelector('.name_output').style.display = 'none';
+    tr.querySelector('.name_show').style.display = 'inline';
+    tr.querySelector('.text_output').style.display = 'none';
+    tr.querySelector('.text_show').style.display = 'inline';
+	tr.querySelector('.type_output').style.display = 'none';
+    tr.querySelector('.type_show').style.display = 'inline';
+}
+
+// Confirm and log deletion action
+function handleDeleteClick(e) {
+    e.preventDefault();
+    const checkConfirm = window.confirm(browser.i18n.getMessage("customPrompts_btnDelete_confirmText"));
+    if (!checkConfirm) {
+        return;
+    }
+    const tr = e.target.parentNode.parentNode;
+    //console.log('>>>>>>>> tr: ' + tr.getAttribute('data-idnum'));
+    customDataPHsList.remove("id", tr.querySelector('span.id').innerText);
+    setSomethingChanged();
+}
+
+function handleCancelClick(e) {
+    e.preventDefault();
+    const tr = e.target.parentNode.parentNode;
+    e.target.style.display = 'none';    // Cancel btn
+    tr.querySelector('.btnConfirmItem').style.display = 'none';   // Save btn
+//        tr.querySelector('.btnCancelItem').style.display = 'none';   // Cancel btn
+    tr.querySelector('.btnEditItem').style.display = 'inline';   // Edit btn
+    tr.querySelector('.btnDeleteItem').style.display = 'inline';   // Delete btn
+    tr.querySelector('.id_output').value = tr.querySelector('.id_show').innerText.toLocaleUpperCase();
+    tr.querySelector('.name_output').value = tr.querySelector('.name_show').innerText;
+    tr.querySelector('.text_output').value = sanitizeHtml(tr.querySelector('.text_show').innerHTML).replace(/<br\s*\/?>/gi, "\n");
+	tr.querySelector('.type_output').value = tr.querySelector('.type').innerText;
+    hideItemRowEditor(tr);
+}
+
+function handleConfirmClick(e) {
+    e.preventDefault();
+    const tr = e.target.parentNode.parentNode;
+    e.target.style.display = 'none';    // Ok btn
+//        tr.querySelector('.btnConfirmItem').style.display = 'none';   // Ok btn
+    tr.querySelector('.btnCancelItem').style.display = 'none';   // Cancel btn
+    tr.querySelector('.btnEditItem').style.display = 'inline';   // Edit btn
+    tr.querySelector('.btnDeleteItem').style.display = 'inline';   // Delete btn
+    // Update item data
+    tr.querySelector('.id_show').innerText = String(tr.querySelector('.id_output').value).toLocaleLowerCase();
+    tr.querySelector('.name_show').innerText = tr.querySelector('.name_output').value;
+    tr.querySelector('.text_show').innerText = tr.querySelector('.text_output').value;
+	tr.querySelector('.type').innerText = tr.querySelector('.type_output').value;
+    tr.querySelector('.type_show').innerText = tr.querySelector('.type_output').selectedOptions[0].text;
+    // the checkboxes update is handled directly by themselves
+    hideItemRowEditor(tr);
+    setSomethingChanged();
+}
+
+// Enable save button on input change
+function handleInputChange(e) {
+    e.preventDefault();
+    setSomethingChanged();
+}
+
+//========= handling an item in a row - END
+
+
+function loadCustomDataPHsList(values){
+    // console.log('>>>>>>>> loadCustomDataPHsList values: ' + JSON.stringify(values));
+    let options = {
+        valueNames: [
+            { data: ['idnum'] },
+            'is_default',
+            'id',
+            'name',
+            'text',
+            'type',
+            { name: 'enabled', attr: 'checked_val'}
+        ],
+        item: function(values) {
+            values.id = placeholdersUtils.stripCustomDataPH_ID_Prefix(values.id);
+            let type_output = '';
+            switch(String(values.type)){
+                case "0":
+                    type_output = `__MSG_customPrompts_add_to_menu_always__`;
+                    break;
+                case "1":
+                    type_output = `__MSG_customPrompts_add_to_menu_reading__`;
+                    break;
+                case "2":
+                    type_output = `__MSG_customPrompts_add_to_menu_composing__`;
+                    break;
+            }
+            let output = `<tr ` + ((values.is_default == 1) ? 'class="is_default"':'') + `>
+                <td class="w08"><i>thunderai_custom_</i><span class="id id_show"></span><input type="text" class="hiddendata id_output" value="` + values.id + `" /></td>
+                <td class="w08"><span class="name name_show"></span><input type="text" class="hiddendata name_output" value="` + values.name + `" /></td>
+                <td class="w40">
+                    <span class="text text_show"></span>
+                    <div class="autocomplete-container">
+                        <textarea class="hiddendata text_output editor">` + values.text.replace(/<br\s*\/?>/gi, "\n") + `</textarea>
+                        <ul class="autocomplete-list hidden"></ul>
+                    </div>
+                </td>
+				<td class="w08"><span class="field_title_s">__MSG_customDataPH_add_to_menu__:</span>
+                <br>
+	                <span class="type_show">` + type_output + `</span>
+	                <select class="type_output hiddendata">
+	                <option value="0"` + ((values.type == "0") ? ' selected':'') + `>__MSG_customPrompts_add_to_menu_always__</option>
+	                <option value="1"` + ((values.type == "1") ? ' selected':'') + `>__MSG_customPrompts_add_to_menu_reading__</option>
+	                <option value="2"` + ((values.type == "2") ? ' selected':'') + `>__MSG_customPrompts_add_to_menu_composing__</option>
+	              </select>` +
+	              `<span class="type hiddendata"></span>
+              </td>
+                <td class="w17">
+                    <label><input type="checkbox" class="enabled input_mod"> __MSG_customPrompts_form_label_enabled__</label>
+                    <span class="is_default hiddendata"></span>
+                    <span class="position_compose hiddendata"></span>
+                    <span class="position_display hiddendata"></span>
+                </td>
+                <td>
+                <button class="btnEditItem"` + ((values.is_default == 1) ? ' disabled':'') + `>__MSG_customPrompts_btnEdit__</button>
+                <button class="btnCancelItem hiddendata"` + ((values.is_default == 1) ? ' disabled':'') + `>__MSG_customPrompts_btnCancel__</button>
+                <br><br>
+                <button class="btnConfirmItem hiddendata"` + ((values.is_default == 1) ? ' disabled':'') + `>__MSG_customPrompts_btnOK__</button>
+                <button class="btnDeleteItem"` + ((values.is_default == 1) ? ' disabled':'') + `>__MSG_customPrompts_btnDelete__</button>
+               </td>
+            </tr>`;
+            //console.log('>>>>>>>> values.name: ' + JSON.stringify(values.name));
+            idnumMax = Math.max(idnumMax, values.idnum);
+            return output;
+        }
+    };
+
+    // console.log('>>>>>>>>>>>>> options: ' + JSON.stringify(options));
+    // console.log('>>>>>>>>>>>>> values: ' + JSON.stringify(values));
+
+    customDataPHsList = new List('all_custom_dataplaceholders', options, values);
+
+    checkSelectedBoxes();
+    let btnEditItem_elements = document.querySelectorAll(".btnEditItem");
+    btnEditItem_elements.forEach(element => {
+        element.addEventListener('click', handleEditClick);
+    });
+
+    let btnDeleteItem_elements = document.querySelectorAll(".btnDeleteItem");
+    btnDeleteItem_elements.forEach(element => {
+        element.addEventListener('click', handleDeleteClick);
+    });
+
+    let btnCancelItem_elements = document.querySelectorAll(".btnCancelItem");
+    btnCancelItem_elements.forEach(element => {
+        element.addEventListener('click', handleCancelClick);
+    });
+
+    let btnConfirmItem_elements = document.querySelectorAll(".btnConfirmItem");
+    btnConfirmItem_elements.forEach(element => {
+        element.addEventListener('click', handleConfirmClick);
+    });
+
+    document.querySelectorAll('.input_mod').forEach(element => {
+        element.addEventListener('change', handleInputChange);
+    });
+}
+
+function checkFields() {
+    //console.log('>>>>>>>>>>>>> typeof customDataPHsList: ' + typeof customDataPHsList);
+    //console.log('>>>>>>>>>>>>> Array.isArray(customDataPHsList): ' + Array.isArray(customDataPHsList));
+    // the id must be unique and without spaces
+    let is_error = false;
+    let id_value = document.getElementById('txtIdNew').value.trim();
+    if ((id_value == '')||
+    (/\s/.test(id_value))) {
+        inputSetError('txtIdNew');
+        is_error = true;
+    } else {
+        let exists = customDataPHsList.get("id", id_value);
+        //console.log('>>>>>>>>>>>>> exists: ' + JSON.stringify(exists));
+        if(exists && exists.length > 0) {
+            inputSetError('txtIdNew');
+            is_error = true;
+        } else {
+            inputClearError('txtIdNew');
+        }
+    }
+    if (document.getElementById('txtNameNew').value.trim() == '') {
+        inputSetError('txtNameNew');
+        is_error = true;
+    } else {
+        inputClearError('txtNameNew');
+    }
+    if (document.getElementById('txtTextNew').value.trim() == '') {
+        inputSetError('txtTextNew');
+        is_error = true;
+    } else {
+        inputClearError('txtTextNew');
+    }
+    document.getElementById('btnAddNew').disabled = is_error;
+    return !is_error;
+}
+
+
+function clearFields() {
+    document.getElementById('txtIdNew').value = '';
+    document.getElementById('txtNameNew').value = '';
+    document.getElementById('txtTextNew').value = '';
+	document.getElementById('selectTypeNew').value = '0';
+    document.getElementById('checkboxNeedSelectedNew').value = '0';
+    document.getElementById('checkboxNeedCustomTextNew').value = '0';
+    document.getElementById('formNew').style.display = 'none';
+}
+
+function inputSetError(input) {
+    document.getElementById(input).style.borderColor = 'red';
+}
+
+function inputClearError(input) {
+    document.getElementById(input).style.borderColor = 'green';
+}
+
+function setSomethingChanged(){
+    clearTimeout(msgTimeout);
+    somethingChanged = true;
+    document.getElementById('btnSaveAll').disabled = false;
+    let msgDisplay = document.getElementById('msgDisplay');
+    msgDisplay.textContent = browser.i18n.getMessage('customPrompts_unsaved_changes');
+    msgDisplay.style.display = 'inline';
+    msgDisplay.style.color = 'red';
+}
+
+function setNothingChanged(){
+    somethingChanged = false;
+    document.getElementById('btnSaveAll').disabled = true;
+    let msgDisplay = document.getElementById('msgDisplay');
+    msgDisplay.disabled = true;
+    msgDisplay.textContent = ''
+    msgDisplay.style.display = 'none';
+    msgDisplay.style.color = '';
+}
+
+function checkSelectedBoxes(checkboxes = null) {
+    if(checkboxes == null){
+        checkboxes = [
+            ...document.querySelectorAll('.enabled[type="checkbox"]'),
+        ];
+    }
+
+    // Iterate through the checkboxes
+    checkboxes.forEach(checkbox => {
+        // Check if the 'checked' attribute is "0"
+        if (checkbox.getAttribute('checked_val') == "0") {
+            // Uncheck the checkbox
+            checkbox.checked = false;
+        } else {
+            checkbox.checked = true;
+        }
+    });
+}
+
+//Save all custom data placeholders
+async function saveAll() {
+    setMessage(browser.i18n.getMessage('customDataPH_saving_custom'));
+    setNothingChanged();
+    if(customDataPHsList != null) {
+        setMessage(browser.i18n.getMessage('customPrompts_reindexing_list'));
+        customDataPHsList.reIndex();
+        let newCustomDataPHs = customDataPHsList.items.filter(item => item.values().is_default == 0).map(item => item.values());
+        taLog.log('newCustomDataPlaceholders: ' + JSON.stringify(newCustomDataPHs));
+        // newCustomDataPHs.forEach(prompt => {
+        //     console.log('>>>>>>>>>>>>> id: ' + JSON.stringify(prompt));
+        // });
+        //console.log('>>>>>>>>>>>>> saveAll: ' + JSON.stringify(newCustomDataPHs));
+        await setCustomPlaceholders(newCustomDataPHs);
+        setMessage(browser.i18n.getMessage('customDataPH_saved'),'green');
+        msgTimeout = setTimeout(() => {
+            clearMessage();
+        }, 10000)
+    }
+    setStorageSpace();
+}
+
+function setMessage(msg, color = '') {
+    clearTimeout(msgTimeout);
+    let msgDisplay = document.getElementById('msgDisplay');
+    msgDisplay.textContent = msg;
+    msgDisplay.style.display = 'inline';
+    msgDisplay.style.color = color;
+}
+
+function clearMessage() {
+    let msgDisplay = document.getElementById('msgDisplay');
+    msgDisplay.textContent = '';
+    msgDisplay.style.display = 'none';
+    msgDisplay.style.color = '';
+}
+
+async function setStorageSpace() {
+    let storage_space = await getLocalStorageUsedSpace();
+    document.getElementById('storage_space').textContent = storage_space;
+}
+
+
+if(await isThunderbird128OrGreater()){
+    window.addEventListener('beforeunload', function (event) {
+        // Check if any changes have been made (Only for Thunderbird 128+ see https://github.com/micz/ThunderAI/issues/88)
+        if (somethingChanged) {
+            event.preventDefault();
+        }
+    });    
+}
\ No newline at end of file
diff --git a/pages/customprompts/mzta-custom-prompts.html b/pages/customprompts/mzta-custom-prompts.html
index 1ac05ee5..30049b14 100644
--- a/pages/customprompts/mzta-custom-prompts.html
+++ b/pages/customprompts/mzta-custom-prompts.html
@@ -11,17 +11,17 @@
         <h1 class="page_title">__MSG_customPrompts_managePrompts__</h1>
         <p>__MSG_customPrompts_managePrompts_info_default__<br>
             __MSG_customPrompts_managePrompts_info_default_2__<br>
-            __MSG_customPrompts_managePrompts_info_default_3__ <a href="https://micz.it/thunderbird-addon-thunderai/custom-prompts/">__MSG_customPrompts_managePrompts_help__</a>
-        <br>__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_customPrompts_managePrompts_help__</a></p>
+            __MSG_customPrompts_managePrompts_info_default_3__ <a href="https://micz.it/thunderbird-addon-thunderai/custom-prompts/">__MSG_more_info_string__</a>
+        <br>__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_more_info_string__</a></p>
     </div>
     <div id="import_export">
         <button id="btnExportAll">__MSG_customPrompts_ExportAll__</button><br>
         <button id="btnImport">__MSG_customPrompts_Import__</button>
     </div>
     <div id="command_palette">
-      <button id="btnSaveAll" disabled>__MSG_customPrompts_btnSaveAll__</button>
+      <button id="btnSaveAll" disabled>__MSG_btnSaveAll_string__</button>
       <span id="msgDisplay"></span>
-      <button id="btnNew">__MSG_customPrompts_btnNew__</button>
+      <button id="btnNew">__MSG_btnNew_string__</button>
     </div>
     <div id="formNew">
       <table class="width_all">
@@ -122,7 +122,7 @@
           </table>
     </div>
     <div class="storage_space">__MSG_StorageSpace__: <span id="storage_space"></span></div>
-    <script src="list.js"></script>
+    <script src="../_lib/list.js"></script>
     <script src="mzta-custom-prompts.js" type="module"></script>
     <script src="../../js/mzta-i18n.js"></script>
 </body>
diff --git a/pages/customprompts/mzta-custom-prompts.js b/pages/customprompts/mzta-custom-prompts.js
index 3b3bbeb2..c4126ce4 100644
--- a/pages/customprompts/mzta-custom-prompts.js
+++ b/pages/customprompts/mzta-custom-prompts.js
@@ -18,9 +18,9 @@
 
 import { prefs_default } from "../../options/mzta-options-default.js";
 import { getPrompts, setDefaultPromptsProperties, setCustomPrompts, preparePromptsForExport, preparePromptsForImport } from "../../js/mzta-prompts.js";
-import { ChatGPTWeb_models, isThunderbird128OrGreater, getCustomPromptsUsedSpace, sanitizeHtml, validateCustomData_ChatGPTWeb, getChatGPTWebModelsList_HTML } from "../../js/mzta-utils.js";
+import { ChatGPTWeb_models, isThunderbird128OrGreater, getLocalStorageUsedSpace, sanitizeHtml, validateCustomData_ChatGPTWeb, getChatGPTWebModelsList_HTML } from "../../js/mzta-utils.js";
 import { taLogger } from "../../js/mzta-logger.js";
-import { getPlaceholders } from "../../js/mzta-placeholders.js";
+import { getPlaceholders, placeholdersUtils } from "../../js/mzta-placeholders.js";
 import { textareaAutocomplete } from "../../js/mzta-placeholders-autocomplete.js";
 
 let prefs = null;
@@ -88,13 +88,13 @@ document.addEventListener('DOMContentLoaded', async () => {
     const textareas = document.querySelectorAll('.editor');
     autocompleteSuggestions = (await getPlaceholders(true)).map(p => ({command: '{%'+p.id+'%}', type: p.type}));
 
-    // console.log('>>>>>>>>>>> suggestions: ' + JSON.stringify(suggestions));
+    // console.log('>>>>>>>>>>> autocompleteSuggestions: ' + JSON.stringify(autocompleteSuggestions));
     
     textareas.forEach(textarea => {
         textareaAutocomplete(textarea, autocompleteSuggestions);
         textareas.forEach(textarea => {
-            textarea.addEventListener('input', (e) => {
-                checkPromptsConfigForPlaceholders(e.target);
+            textarea.addEventListener('input', async (e) => {
+                await checkPromptsConfigForPlaceholders(e.target);
             });
         textareaAutocomplete(textarea, autocompleteSuggestions);
         });
@@ -161,7 +161,6 @@ document.addEventListener('DOMContentLoaded', async () => {
         }
     });
 
-
     //To add a new item
     var txtIdNew = document.getElementById('txtIdNew');
     var txtNameNew = document.getElementById('txtNameNew');
@@ -588,13 +587,13 @@ function handleConfirmClick(e) {
 }
 
 // Handle checkbox changes and log new state
-function handleCheckboxChange(e) {
+async function handleCheckboxChange(e) {
     e.preventDefault();
     e.target.setAttribute('checked_val', e.target.checked ? '1' : '0');
     //console.log('>>>>>>>> checked_val: ' + e.target.getAttribute('checked_val'));
     if (e.target.classList.contains('need_selected') || e.target.classList.contains('need_custom_text') || e.target.classList.contains('need_selected_new') || e.target.classList.contains('need_custom_text_new')) {
         let textarea = e.target.closest('tr').querySelector('.text_output');
-        checkPromptsConfigForPlaceholders(textarea);
+        await checkPromptsConfigForPlaceholders(textarea);
     }
     
 }
@@ -936,7 +935,7 @@ function clearMessage() {
 }
 
 async function setStorageSpace() {
-    let storage_space = await getCustomPromptsUsedSpace();
+    let storage_space = await getLocalStorageUsedSpace();
     document.getElementById('storage_space').textContent = storage_space;
 }
 
@@ -950,11 +949,15 @@ if(await isThunderbird128OrGreater()){
     });    
 }
 
-function checkPromptsConfigForPlaceholders(textarea){
+async function checkPromptsConfigForPlaceholders(textarea){
+    let curr_text = textarea.value;
+    // First substitute the custom data placeholders
+    curr_text = await placeholdersUtils.replaceCustomPlaceholders(curr_text);
+    console.log('>>>>>>>>>> curr_text after custom placeholders: ' + curr_text);
     // check additional_text and selected_text placeholders presence and the corrispondent checkboxes
     let tr_ancestor = textarea.closest('tr');
     let need_custom_text_element = tr_ancestor.querySelector('.need_custom_text') || tr_ancestor.querySelector('.need_custom_text_new');
-    if(String(textarea.value).indexOf('{%additional_text%}') != -1){
+    if(String(curr_text).indexOf('{%additional_text%}') != -1){
         if(!need_custom_text_element.checked){
             need_custom_text_element.closest('.need_custom_text_span').style.border = '2px solid red';
         }else{
@@ -966,7 +969,7 @@ function checkPromptsConfigForPlaceholders(textarea){
 
       let tr_ancestor2 = textarea.closest('tr');
       let selected_text_element = tr_ancestor2.querySelector('.need_selected') || tr_ancestor2.querySelector('.need_selected_new');
-      if((String(textarea.value).indexOf('{%selected_text%}') != -1)||(String(textarea.value).indexOf('{%selected_html%}') != -1)){
+      if((String(curr_text).indexOf('{%selected_text%}') != -1)||(String(curr_text).indexOf('{%selected_html%}') != -1)){
         if(!selected_text_element.checked){
             selected_text_element.closest('.need_selected_span').style.border = '2px solid red';
         }else{
diff --git a/pages/get-calendar-event/mzta-get-calendar-event.html b/pages/get-calendar-event/mzta-get-calendar-event.html
index 911d0682..10e6d1cc 100644
--- a/pages/get-calendar-event/mzta-get-calendar-event.html
+++ b/pages/get-calendar-event/mzta-get-calendar-event.html
@@ -57,7 +57,7 @@
     </table>
     <div id="get_calendar_event_container">
         <span class="section_title">__MSG_GetCalendarEvent_prompt_text_title__</span><span id="get_calendar_event_prompt_unsaved" class="unsaved hidden"> __MSG_customPrompts_unsaved_changes__</span>
-        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_customPrompts_managePrompts_help__</a>
+        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_more_info_string__</a>
           <br><b>__MSG_prefs_OptionText_AdvancedPromptResponse_infoline2__</b></span>
         <br>
         <div class="autocomplete-container">
diff --git a/pages/get-task/mzta-get-task.html b/pages/get-task/mzta-get-task.html
index f5f32028..6e8e5f15 100644
--- a/pages/get-task/mzta-get-task.html
+++ b/pages/get-task/mzta-get-task.html
@@ -57,7 +57,7 @@
     </table>
     <div id="get_task_container">
         <span class="section_title">__MSG_GetCalendarEvent_prompt_text_title__</span><span id="get_task_prompt_unsaved" class="unsaved hidden"> __MSG_customPrompts_unsaved_changes__</span>
-        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_customPrompts_managePrompts_help__</a>
+        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_more_info_string__</a>
           <br><b>__MSG_prefs_OptionText_AdvancedPromptResponse_infoline2__</b></span>
         <br>
         <div class="autocomplete-container">
diff --git a/pages/spamfilter/mzta-spamfilter.html b/pages/spamfilter/mzta-spamfilter.html
index 1c82ac12..9c7b4fd3 100644
--- a/pages/spamfilter/mzta-spamfilter.html
+++ b/pages/spamfilter/mzta-spamfilter.html
@@ -34,7 +34,7 @@
     </table>
     <div id="spamfilter_container">
         <span class="section_title">__MSG_SpamFilter_prompt_text_title__</span><span id="spamfilter_prompt_unsaved" class="unsaved hidden"> __MSG_customPrompts_unsaved_changes__</span>
-        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_customPrompts_managePrompts_help__</a>
+        <br><span class="infoline">__MSG_prefs_OptionText_btnManagePrompts_infoline__ <a href="https://micz.it/thunderbird-addon-thunderai/data-placeholders/">__MSG_more_info_string__</a>
           <br><b>__MSG_prefs_OptionText_AdvancedPromptResponse_infoline2__</b></span>
         <br>
         <div class="autocomplete-container">