No INcoming mail

I do not have the SMTP proxy option, so I want just be able to open smtp port (25) on the UTM 425 and send mail straight through to my exchange 2003 server. I can send mail out of that server, ever mail that is coming in it port blocked, the live log show everything is red, therefore being dropped out.

I have made rules to allow email traffic, and smtp traffic to my inter IP email server.

any ideas?