We are running Exchange 2003 and are starting to see more and more SMTP 550 5.5.0 Errors that I believe are due to other servers doing and anti-spam reverse DNS lookup on our server name. I have a DNS Host Record set up as MAIL.XYZ.COM resolves to our External IP Address, and an MX Record points to MAIL.XYZ.COM.
To other mail servers, the address of our Exchange Server is MAIL.DOMAIN_1.XYZ.COM.
The Mail Server is named MAIL, our Windows 2000 Domain Name is DOMAIN_1 and our public domain name is XYZ.COM.
99.99% of emails work fine, I am just starting to see more and more mail rejected with the SMTP 550 error. How can I get our Exchange server to send external mail as MAIL.XYZ.COM instead of using the internal domain name?