diff --git a/mail/base/content/mailContext.js b/mail/base/content/mailContext.js
index 2dedceec38..c709669bae 100644
--- a/mail/base/content/mailContext.js
+++ b/mail/base/content/mailContext.js
@@ -326,9 +326,7 @@ var mailContextMenu = {
       this.context?.onVideo ||
       this.context?.onTextInput;
 
-    for (const id of ["mailContext-tags", "mailContext-mark"]) {
-      showItem(id, !onSpecialItem);
-    }
+    showItem("mailContext-tags", !onSpecialItem);
 
     // Ask commandController about the commands it controls.
     for (const [id, command] of Object.entries(this._commands)) {
@@ -393,7 +391,6 @@ var mailContextMenu = {
       this._initMessageTags();
     }
 
-    showItem("mailContext-mark", !isDummyMessage);
     checkItem("mailContext-markFlagged", message?.isFlagged);
 
     setSingleSelection("mailContext-copyMessageUrl", !!isNewsgroup);
@@ -447,6 +444,12 @@ var mailContextMenu = {
       window.threadTree && numSelectedMessages > 1
     );
 
+    this._ensureSubmenuVisibility();
+    // Special case: mark menu shouldn't be shown on external messages.
+    if (isDummyMessage) {
+      showItem("mailContext-mark", false);
+    }
+
     let lastItem;
     for (const child of document.getElementById("mailContext").children) {
       if (child.localName == "menuseparator") {
@@ -498,6 +501,21 @@ var mailContextMenu = {
     Services.obs.notifyObservers(subject, "on-build-contextmenu");
   },
 
+  /**
+   * Hide all top level submenus of the context menu that have no visibile items.
+   * Ignores separators since they are only a visual aid for the user and not
+   * actual features making the menu worth showing. Excludes generated submenus.
+   */
+  _ensureSubmenuVisibility() {
+    for (const menu of document.querySelectorAll(
+      "#mailContext > menu:not(#mailContext-tags,#mailContext-moveMenu,#mailContext-copyMenu)"
+    )) {
+      menu.hidden = Array.from(menu.menupopup.children).every(
+        child => child.hidden || child.localName === "menuseparator"
+      );
+    }
+  },
+
   onMailContextMenuCommand(event) {
     // If commandController handles this command, ask it to do so.
     if (event.target.id in this._commands) {
diff --git a/mail/base/test/browser/browser_mailContext.js b/mail/base/test/browser/browser_mailContext.js
index 9b1b22a78b..dc2b6c94b3 100644
--- a/mail/base/test/browser/browser_mailContext.js
+++ b/mail/base/test/browser/browser_mailContext.js
@@ -141,16 +141,16 @@ const mailContextData = {
     "templatesFolderTree",
     "multipleTemplatesFolderTree",
   ],
-  "mailContext-open": true,
-  "mailContext-reply": true,
-  "mailContext-forwardRedirect": true,
+  "mailContext-open": [...singleNotExternal, "collapsedThreadTree"],
+  "mailContext-reply": noCollapsedThreads,
+  "mailContext-forwardRedirect": noCollapsedThreads,
   "mailContext-editAsNew": noCollapsedThreads,
   "mailContext-moveMenu": notExternal,
   "mailContext-copyMenu": true,
   "mailContext-tags": notExternal,
   "mailContext-mark": notExternal,
-  "mailContext-organize": true,
-  "mailContext-threads": true,
+  "mailContext-organize": notExternal,
+  "mailContext-threads": [...notSynthetic, ...onePane],
   "mailContext-saveAs": true,
   "mailContext-print": true,
   "mailContext-downloadSelected": [
@@ -206,7 +206,7 @@ function checkMenuitems(menu, mode) {
     );
   }
 
-  Assert.deepEqual(actualItems, expectedItems);
+  Assert.deepEqual(actualItems, expectedItems, `Mode: ${mode}`);
 
   menu.hidePopup();
 }