diff --git a/js/mzta-compose-script.js b/js/mzta-compose-script.js
index 6b1d7fab..b4091b1e 100644
--- a/js/mzta-compose-script.js
+++ b/js/mzta-compose-script.js
@@ -26,6 +26,20 @@ const MZTA_INJECTED_SELECTORS = [
   '.mzta_dialog',
 ];
 
+// Mirrors removeMozMainHeader() from mzta-utils.js.
+// Removes the Thunderbird-injected header table and any preceding divs.
+function removeMozMainHeader(root) {
+  const table = root.querySelector('table.moz-main-header');
+  if (!table) return;
+  let sibling = table.previousElementSibling;
+  while (sibling && sibling.tagName === 'DIV') {
+    const toRemove = sibling;
+    sibling = sibling.previousElementSibling;
+    toRemove.remove();
+  }
+  table.remove();
+}
+
 function getCleanBodyClone() {
   const clone = document.body.cloneNode(true);
   for (const selector of MZTA_INJECTED_SELECTORS) {
@@ -33,6 +47,7 @@ function getCleanBodyClone() {
       el.remove();
     }
   }
+  removeMozMainHeader(clone);
   return clone;
 }
 
diff --git a/js/mzta-utils.js b/js/mzta-utils.js
index b3048c30..71f876b3 100644
--- a/js/mzta-utils.js
+++ b/js/mzta-utils.js
@@ -181,6 +181,11 @@ export function getMailBody(fullMessage){
   }
   if(html === "") {
     html = text.replace(/\n/g, "<br>");
+  } else {
+    const parser = new DOMParser();
+    const doc = parser.parseFromString(html, 'text/html');
+    removeMozMainHeader(doc.body);
+    html = doc.body.innerHTML;
   }
   return {text, html};
 }
@@ -246,7 +251,9 @@ export function htmlBodyToPlainText(htmlString) {
 	const parser = new DOMParser();
 	// Parse the HTML string
 	const doc = parser.parseFromString(htmlString, 'text/html');
-	
+
+  removeMozMainHeader(doc.body);
+
   // remove invisible elements https://stackoverflow.com/questions/39813081/queryselector-where-display-is-not-none
    // return doc;
   doc.querySelectorAll('[style*="display:none"]').forEach(e => e.remove());//.querySelector('html').children.not(':visible').remove()
@@ -263,7 +270,19 @@ export function htmlBodyToPlainText(htmlString) {
   .replace(/&nbsp;/gi,"")
   .trim();
 }
- 
+
+export function removeMozMainHeader(root) {
+  const table = root.querySelector('table.moz-main-header');
+  if (!table) return;
+  let sibling = table.previousElementSibling;
+  while (sibling && sibling.tagName === 'DIV') {
+    const toRemove = sibling;
+    sibling = sibling.previousElementSibling;
+    toRemove.remove();
+  }
+  table.remove();
+}
+
 export function cleanupNewlines(text) {
   return text
   .replace(/\r\n/g, '\n')