I hope you can help me.
I am running Exchange Server 2003 in my organization. The server sits on the Active Directory server and the DNS Server as well. I have configured my company's domain name ntsoftware.com.my on it so that the emails will go out as firstname.lastname@example.org.
I have configured a reverse lookup zone and forward lookup zone correctly for my mail server (with PTR and MX Records) and my mails can go out fine.
However, when userA send mails to this particular domain, say domainXYZ.com, the mails bounce back with this error.
<mxserver.ntsoftware.com.my #5.1.8 smtp;553 5.1.8
<userA@ntsoftware.com.my>... Domain of sender address
userA@ntsoftware.com.my does not exist>
I have gone thru many archives but I can't seem to find the answer! Please help!