ActiveSync does not send E-Mails

ActiveSync does not send E-Mails

Hello,

i have connected my Zoho Mail Account to Outlook 2013 via Active Sync. Mail, Folders, Contacts and Calendar are synced to Outlook 2013. But if i try to send a E-Mail, the Mail comes back to my Inbox with the following error:


This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.

someaccount@mydomain.com Error, ERROR_CODE :550, ERROR_CODE :5.7.0 (COL004-MC2F8) Message could not be delivered. Please ensure the message is RFC 5322 compliant.


Received:from mail.zoho.com by mx.zohomail.com
    with SMTP id 1444160545529791.8290156832579; Tue, 6 Oct 2015 12:42:25 -0700 (PDT)
Message-ID:< 1503ead22c7.10aedc30e24871.50622791118173431432@zoho.com>
Date:Tue, 6 Oct 2015 21:42:24 +0200
From:Me < mymail@zoho.com>
User-Agent:Zoho Mail
To:< someaccount@mydomain.com>
Subject:Neuer Test Outlook 2013
Content-Type:multipart/alternative;
    boundary="----=_NextPart_000_0086_01D1007F.E389A3B0"