Autoforwarded emails to an external party is being rejected by their email server. It says Relay Access is denied. Possibly because our email server internal server domain is pigeon.zentree.lan but our email domain is @zentreecompany.com (all domains are examples/ficticious). Any suggestions on how to resolve this? Many Thanks.
Delivery has failed to these recipients or distribution lists:
A communication failure occurred during the delivery of this message. Microsoft Exchange will not try to redeliver this message for you. Please try resending this message later, or provide the following diagnostic text to your system administrator.
The following organization rejected your message: VA3EHSMHS031.bigwhale.com.
Sent by Microsoft Exchange Server 2007
Diagnostic information for administrators:
Generating server: pigeon.zentree.lan
VA3EHSMHS031.bigwhale.com #550 5.4.1 Relay Access Denied ##rfc822;firstname.lastname@example.org
Original message headers:
Received: from pigeon.zentree.lan ([::1]) by pigeon.zentree.lan ([::1]) with