Can't receive email on one domain

[dean_danis]

We have a server that hosts several domains such as domain1.com and domain2.com. Email service was recently changed on domain1.com to anther server and the MX records where adjusted via Plesk 8.6 to point to the new server. Everything seems to be working OK except that emails sent from domain2.com do not arrive at domain1.com. Emails still arrive to domain1.com if sent from any other server, but not if they originate from doamin2.com or any other domain on that server.

Any insights or assistance would be helpful, thanks.