diff --git a/NEWS b/NEWS
index aa7e84434..8d2204d4c 100644
--- a/NEWS
+++ b/NEWS
@@ -15,6 +15,7 @@ Enhancements
  - updated Finnish translation
  - XMLHttpRequest.js is now loaded conditionaly (< IE9)
  - format time in attendees invitation window according to the user's locale
+ - improved IE11 support
 
 Bug fixes
  - don't load 'background' attribute (#2437)
diff --git a/UI/Templates/MailerUI/UIxMailEditor.wox b/UI/Templates/MailerUI/UIxMailEditor.wox
index b5fe79da3..ea18d9c4f 100644
--- a/UI/Templates/MailerUI/UIxMailEditor.wox
+++ b/UI/Templates/MailerUI/UIxMailEditor.wox
@@ -123,7 +123,7 @@
         </ul>
       </div>
     </div><!-- #headerArea -->
-    <textarea id="text" name="text" rows="30" var:value="text"></textarea>
+    <textarea id="text" name="text" rows="25" style="display:none" var:value="text"/>
   </form>
   </div>
 
diff --git a/UI/WebServerResources/UIxMailEditor.css b/UI/WebServerResources/UIxMailEditor.css
index 019401d08..6590507a3 100644
--- a/UI/WebServerResources/UIxMailEditor.css
+++ b/UI/WebServerResources/UIxMailEditor.css
@@ -200,8 +200,7 @@ UL#attachments .progressDone .icon-attachment:hover
 { width: 99%; }
 
 TEXTAREA#text
-{ display: none;
-  background: #fff; }
+{ background: #fff; }
 
 #cke_text
 { clear: both; }
diff --git a/UI/WebServerResources/UIxMailEditor.js b/UI/WebServerResources/UIxMailEditor.js
index debe65db1..d8b7f13d1 100644
--- a/UI/WebServerResources/UIxMailEditor.js
+++ b/UI/WebServerResources/UIxMailEditor.js
@@ -255,18 +255,20 @@ function clickedEditorSave() {
     return false;
 }
 
+/**
+ * On first focus of textarea, position the caret with respect to user's preferences
+ */
 function onTextFocus(event) {
     if (MailEditor.textFirstFocus) {
-        // On first focus, position the caret at the proper position
         var content = this.getValue();
         var replyPlacement = UserDefaults["SOGoMailReplyPlacement"];
-        if (replyPlacement == "above" || !mailIsReply) { // for forwards, place caret at top unconditionally
+        if (replyPlacement == "above" || !mailIsReply) {
+            // For forwards, place caret at top unconditionally
             this.setCaretTo(0);
         }
         else {
             var caretPosition = this.getValue().length - MailEditor.signatureLength;
-            if (Prototype.Browser.IE)
-                caretPosition -= lineBreakCount(this.getValue().substring(0, caretPosition));
+            caretPosition = adjustOffset(this, caretPosition);
             if (hasSignature())
                 caretPosition -= 2;
             this.setCaretTo(caretPosition);
@@ -275,10 +277,13 @@ function onTextFocus(event) {
     }
 }
 
+/**
+ * Change behavior of tab key in textarea (plain-text mail)
+ */
 function onTextKeyDown(event) {
     if (event.keyCode == Event.KEY_TAB) {
-        // Change behavior of tab key in textarea
         if (event.shiftKey) {
+            // Shift-tab goes back to subject field
             var subjectField = $$("div#subjectRow input").first();
             subjectField.focus();
             subjectField.selectText(0, subjectField.value.length);
@@ -287,8 +292,7 @@ function onTextKeyDown(event) {
         else {
             if (!(event.shiftKey || event.metaKey || event.ctrlKey)) {
                 // Convert a tab to 4 spaces
-                if (typeof(this.selectionStart)
-                    != "undefined") { // For Mozilla and Safari
+                if (typeof(this.selectionStart) != "undefined") { // Mozilla and Safari
                     var cursor = this.selectionStart;
                     var startText = ((cursor > 0)
                                      ? this.value.substr(0, cursor)
@@ -301,8 +305,6 @@ function onTextKeyDown(event) {
                 }
                 else if (this.selectionRange) // IE
                     this.selectionRange.text = "    ";
-                else { // others ?
-                }
                 preventDefault(event);
             }
         }
@@ -313,13 +315,6 @@ function onTextIEUpdateCursorPos(event) {
     this.selectionRange = document.selection.createRange().duplicate();
 }
 
-function onTextMouseDown(event) {
-    if (event.button == 0) {
-        event.returnValue = false;
-        event.cancelBubble = false;
-    }
-}
-
 function onHTMLFocus(event) {
     if (MailEditor.textFirstFocus) {
         var s = event.editor.getSelection();
@@ -471,14 +466,15 @@ function configureAttachments() {
 }
 
 function initMailEditor() {
+    var textarea = $("text");
+
     if (composeMode != "html" && $("text"))
-        $("text").style.display = "block";
+        textarea.show();
 
     configureAttachments();
   
     initAddresses();
 
-    var textarea = $("text");
     var focusField = textarea;
     if (!mailIsReply) {
         focusField = $("addr_0");
@@ -527,10 +523,10 @@ function initMailEditor() {
             textarea.scrollTop = textarea.scrollHeight;
         }
         textarea.observe("focus", onTextFocus);
-        //textarea.observe("mousedown", onTextMouseDown);
         textarea.observe("keydown", onTextKeyDown);
 
         if (Prototype.Browser.IE) {
+            // Hack to allow to replace the tab by spaces in IE < 9
             var ieEvents = [ "click", "select", "keyup" ];
             for (var i = 0; i < ieEvents.length; i++)
                 textarea.observe(ieEvents[i], onTextIEUpdateCursorPos, false);
@@ -542,10 +538,7 @@ function initMailEditor() {
 
     $("contactFolder").observe("change", onContactFolderChange);
     
-    Event.observe(window, "resize", onWindowResize);
     Event.observe(window, "beforeunload", onMailEditorClose);
-    
-    onWindowResize.defer();
 }
 
 function initializePriorityMenu() {
@@ -606,13 +599,16 @@ function attachmentDeleteCallback(http) {
     }
 }
 
-function lineBreakCount(str){
-    /* counts \n */
-    try {
-        return((str.match(/[^\n]*\n[^\n]*/gi).length));
-    } catch(e) {
-        return 0;
+/**
+ * Adjust offset when the browser uses two characters for line feeds.
+ */
+function adjustOffset(element, offset) {
+    var val = element.value, newOffset = offset;
+    if (val.indexOf("\r\n") > -1) {
+        var matches = val.replace(/\r\n/g, "\n").slice(0, offset).match(/\n/g);
+        newOffset -= matches ? matches.length - 1 : 0;
     }
+    return newOffset;
 }
 
 function hasSignature() {
@@ -646,6 +642,9 @@ function onSelectOptions(event) {
     }
 }
 
+/**
+ * Overwrite definition of MailerUI.js
+ */
 function onWindowResize(event) {
     if (!document.pageform)
       return;