--- a/editor/libeditor/HTMLEditorDataTransfer.cpp
+++ b/editor/libeditor/HTMLEditorDataTransfer.cpp
@@ -1549,71 +1549,72 @@ HTMLEditor::CanPasteTransferable(nsITran
     if (NS_SUCCEEDED(rv) && data) {
       return true;
     }
   }
 
   return false;
 }
 
-/**
- * HTML PasteAsQuotation: Paste in a blockquote type=cite.
- */
 NS_IMETHODIMP
 HTMLEditor::PasteAsQuotation(int32_t aSelectionType)
 {
   if (IsPlaintextEditor()) {
     return PasteAsPlaintextQuotation(aSelectionType);
   }
 
-  nsAutoString citation;
-  return PasteAsCitedQuotation(citation, aSelectionType);
-}
+  // If it's not in plain text edit mode, paste text into new
+  // <blockquote type="cite"> element after removing selection.
 
-NS_IMETHODIMP
-HTMLEditor::PasteAsCitedQuotation(const nsAString& aCitation,
-                                  int32_t aSelectionType)
-{
   AutoPlaceholderBatch beginBatching(this);
   AutoTopLevelEditSubActionNotifier maybeTopLevelEditSubAction(
                                       *this, EditSubAction::eInsertQuotation,
                                       nsIEditor::eNext);
 
-  // get selection
   RefPtr<Selection> selection = GetSelection();
-  NS_ENSURE_TRUE(selection, NS_ERROR_NULL_POINTER);
+  if (NS_WARN_IF(!selection)) {
+    return NS_ERROR_FAILURE;
+  }
 
-  // give rules a chance to handle or cancel
+  // Adjust Selection and clear cached style before inserting <blockquote>.
   EditSubActionInfo subActionInfo(EditSubAction::eInsertElement);
   bool cancel, handled;
-  // Protect the edit rules object from dying
   RefPtr<TextEditRules> rules(mRules);
   nsresult rv =
     rules->WillDoAction(selection, subActionInfo, &cancel, &handled);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;
   }
   if (cancel || handled) {
-    return NS_OK; // rules canceled the operation
+    return NS_OK;
   }
 
+  // Then, remove Selection and create <blockquote type="cite"> now.
+  // XXX Why don't we insert the <blockquote> into the DOM tree after
+  //     pasting the content in clipboard into it?
   nsCOMPtr<Element> newNode =
     DeleteSelectionAndCreateElement(*nsGkAtoms::blockquote);
-  NS_ENSURE_TRUE(newNode, NS_ERROR_NULL_POINTER);
-
-  // Try to set type=cite.  Ignore it if this fails.
+  if (NS_WARN_IF(!newNode)) {
+    return NS_ERROR_FAILURE;
+  }
   newNode->SetAttr(kNameSpaceID_None, nsGkAtoms::type,
                    NS_LITERAL_STRING("cite"), true);
 
-  // Set the selection to the underneath the node we just inserted:
+  // Collapse Selection in the new <blockquote> element.
   rv = selection->Collapse(newNode, 0);
-  NS_ENSURE_SUCCESS(rv, rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
 
   // XXX Why don't we call HTMLEditRules::DidDoAction() after Paste()?
-  return Paste(aSelectionType);
+  rv = Paste(aSelectionType);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+  return NS_OK;
 }
 
 /**
  * Paste a plaintext quotation.
  */
 nsresult
 HTMLEditor::PasteAsPlaintextQuotation(int32_t aSelectionType)
 {

--- a/editor/libeditor/TextEditor.cpp
+++ b/editor/libeditor/TextEditor.cpp
@@ -1934,23 +1934,16 @@ TextEditor::InsertAsQuotation(const nsAS
       *aNodeInserted = nullptr;
     }
   }
   // XXX Why don't we call TextEditRules::DidDoAction()?
   return rv;
 }
 
 NS_IMETHODIMP
-TextEditor::PasteAsCitedQuotation(const nsAString& aCitation,
-                                  int32_t aSelectionType)
-{
-  return NS_ERROR_NOT_IMPLEMENTED;
-}
-
-NS_IMETHODIMP
 TextEditor::InsertAsCitedQuotation(const nsAString& aQuotedText,
                                    const nsAString& aCitation,
                                    bool aInsertHTML,
                                    nsINode** aNodeInserted)
 {
   return InsertAsQuotation(aQuotedText, aNodeInserted);
 }
 

--- a/editor/nsIEditorMailSupport.idl
+++ b/editor/nsIEditorMailSupport.idl
@@ -35,25 +35,16 @@ interface nsIEditorMailSupport : nsISupp
    * as plaintext quoted blocks.
    * If the selection is not collapsed, the selection is deleted
    * and the insertion takes place at the resulting collapsed selection.
    *
    * @param aString   the string to be inserted
    */
    void insertTextWithQuotations(in DOMString aStringToInsert);
 
-  /** Paste a string as quoted text,
-    * whose representation is dependant on the editor type,
-    * replacing the selected text (if any)
-    * @param aCitation    The "mid" URL of the source message
-    * @param aSelectionType Text or html?
-    */
-  void pasteAsCitedQuotation(in AString aCitation,
-                             in long aSelectionType);
-
   /** Insert a string as quoted text
     * (whose representation is dependant on the editor type),
     * replacing the selected text (if any),
     * including, if possible, a "cite" attribute.
     * @param aQuotedText  The actual text to be quoted
     * @param aCitation    The "mid" URL of the source message
     * @param aInsertHTML  Insert as html?  (vs plaintext)
     * @return             The node which was inserted