I'm in a situation where we need to drop our old Exchange 2003 server (don't ask me why it's still alive ;)) in favor of a mid-hop Exchange 2010 and then we'll migrate to 2013 Soon™.
Anyhow - the 2010 server's set up and I've moved one mailbox to it.
The mailbox can send and receive mails within the organization (2003<->2010) just fine. It can send mails to internet, but not receive mails from internet.
We've got a antispam/antivirus server as a smart host in front of our Exchange 2003.
So .. Internet -> Trend IMSVA -> Exchange 2003 -> Exchange 2010
What's needed on the Exchange 2003 in order for it to forward the mails to the mailbox on the 2010 server?
I've tried all kinds of various methods, but haven't been able to nail it yet.
I'm pressed in order to get this working ASAP - hence the high points.