         if html? and not text? and not message.composeInHTML
             text = toMarkdown html
 
-        if (inReplyTo = props.inReplyTo)
+        inReplyTo = props.inReplyTo
+        inReplyTo = null if inReplyTo and _.isString inReplyTo
+        if inReplyTo
+            replyID = inReplyTo.get 'id'
+            html = inReplyTo?.get 'html'
             _.extend message,
-                inReplyTo: [replyID = inReplyTo.get 'id']
+                inReplyTo: inReplyTo
                 references: (inReplyTo.get('references') or []).concat replyID
 
         isSignature = !!!_.isEmpty(signature = account.signature)

        message.cc = []
        message.bcc = []
        message.subject = @getReplySubject inReplyTo
        message.text = separator + @generateReplyText(text) + "\n"
        message.html = """
        #{COMPOSE_STYLE}
        <p><br></p>


    # Extract a reply address from a `message` object.
    getReplyToAddress: (message) ->
        reply = message?.get 'replyTo'
        from = message?.get 'from'
        if (reply? and reply.length isnt 0)
            return reply
        else
