I am getting Message not sent error marked critical. Rejected addresses. These are good emails and go in gmail. I went to admin to check some of Phoenix' fixes. and get this error

Message: system failure: exception during auth {RemoteManager: mail.dataforcecrm.com->zimbra@mail.dataforcecrm.com:22}
Error code: service.FAILURE
Method: ZmCsfeCommand.prototype.invoke
Details:soap:Receiver

Please suggest how to fix. Thanks JR