We are using some kind of generic SMTP server and want to migrate to Exchange 2007 (abc.com). But we want to do it gradually (to keep both server running temporarily),below is what we supposed todo:1) select some users and set their accounts on the SMTP serverto foward all email receivedto Exchange2) route all external email from Exchange 2007 to SMTP serverNow, we have a problem because Exchange will see abc.com as internal domain and will not route the emails externally. As a result, users sent from Exchange to abc.com will not go back to the SMTP server and they never get through.How to tell Exchange to route local emails too?

Hi,Can you explain things in more detail?Do you have same email addresses (*@abc.com) for both generic SMTP server and Exchange 2007 server? If so, you need to configure your exchange to route message for a shared address space in case users are not available on local Exchange 2007 server. Check out below article...How to Configure Exchange 2007 to Route Messages for a Shared Address Spacehttp://technet.microsoft.com/en-us/library/bb676395.aspx Amit Tank | MVP - Exchange | MCITP:EMA MCSA:M | http://ExchangeShare.WordPress.com

Yes, you're right. Both generic SMTP and Exchange share the same e-mail domain (eg. abc.com) Now I want to migrate user1 and user2 separately so I can test out the settings and every other things. User1 continue using the generic SMTP server while User2 migrated to abc.com. And all incoming email to user2@abc.com willgo through the generic SMTP (because MX record is directed to it) server first, then forward to Exchange. No problem at that part, both user can get emails. The problem is in outgoing emails. When user1 send email to user2, no problem still because it will forward to user2's Exchange account. User2 can also send email to outside domain (eg. user3@anotherdomain.com) But when user2 send an email to user1, user1 cannot get it because Exchange will not route email local to "abc.com" to another server.

Hi, Did you set the abc.com in Exchange 2007 as the Internal Relay Domain? And the corresponding send connector also is needed so that it can send the email to the user in the generic SMTP? Thanks Allen

Yes, I set it as Internal Relay and then set a send connector for abc.com, route through the generic SMTP server. But still doesn't work.

I read the link supplied http://technet.microsoft.com/en-us/library/bb676395.aspx. According to the document, Exchange will send email first within its own organization before redirected through the "Send Connector". If this is the case, I cannot achieve what I want to do with Exchange?