We have our email domain hosted on two mail servers. One is Exchange 2003 on a SBS 2003 box within our network and the other is MDaemon Mail Server hosted on a Windows 2003 Server in a remote public facing location.
The reason why is user cost based. Our central core of employees all have exchange based accounts and the rest are freelancers that have cheaper cost per user accounts on the remote server. Both servers are configured to process mail for our company email domain.. lets call it 'companymail.com' for now The mail flow is as follows;
All mail comes in via the remote MDaemon mail server. Any mail for accounts setup on this remote server get delivered at this stage, any unknown mail gets forwarded to the Exchange server. The exchange server then delivers any email it recieves from the MDaemon server to its accounts. I have set up an SMTP connector to route all outgoing mail through the remote MDaemon server.
As far as I could see, all was working fine untill I was asked to forward mail from an Exchange user (firstname.lastname@example.org) to a user on the remote Mdaemon server (email@example.com). I entered a contact in AD and assigned it the SMTP email address firstname.lastname@example.org. Now when I sent a mail to email@example.com it did not forward to firstname.lastname@example.org. I assumed that since I routed all email via the remote MDaemon server then it would forward ok. The undeliverable message I get back is;
"A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients. Contact your administrator."
Any help gratefully recieved!