I have a client that has two domains with accounts in each. I am currently rolling out Exchange 2003. Is it possible to have both domains access one Exchange server using the accounts in each domain?

Yes, it is. See http://support.microsoft.com/kb/268838and http://www.microsoft.com/technet/prodtechnol/exchange/Guides/E2k3FrontBack/9b27d424-9ac9-4cf3-920b-80d9e10ab7ab.mspx?mfr=truefor more information.

the first link procedure I know but that doesn't work. I also made MX records for another domain to link up with exchange. But clients are not able to connect to another domain but the first one works fine. And the other link is not working. Please help !!!