Exchange 2010 on win2k8 r2.
Branch office(A) using external mail hosting(mail.domanA.com) so the mail domain is not same as hq. Inside the AD and Exchange 2010 in hq, got A's staff windows accounts and mailboxes. The mailboxes primary email is point to hq's domain(mail.domanHQ.com). In order to send message to A's staff and they able to receive the message, I must add the external email address for them each. I did that, and also set the external email adress as a primary email. By this configuration, when HQ's staff send message to A's staff, A's staff able to receive message by their mail.domainA.com account. But i aware that A's staff receive none from HQ's staff and I found out that all messages sent by HQ's staff are inside the exchange mailboxes(reside in mail.domainHQ.com).
I restarted all the exchange services but still same result. please help and advise. thank you.