OK, I'm not quite sure where to post this since it covers a few topics, but at the core, its a mail question, so here goes!
THE CORE QUESTION:
How do I restrict port 25 to only receiving mail from our spam filtering service (postini) without making the iphones unable to get mail?
We've have exchange 2007. we've recently setup postini (for those not familiar: a spam filltering service. we change out MX records to hit their site, filter the spam, then the mail gets sent to out to our IP from them. We also send out mail out through them from our exchange box)
Part of the setup requires us to only accept port 25 connections from so that we can setup a "secure relay" on our server for when the have to reinject a message.
We have users that have iphones that connect to our IP or mail.domain.com to grab mail. only allowing port 25 connections from postini makes the phones unable to connect. Does anyone know a way around this? can exchange receive on port 25 and another port at the same time? maybe there is a firewall rule i'm not thinking of?
I had to open the rule for a while, and got hit hard with spam, probobly someone trying to relay off our server. queues were filled up big time.
I know this is a lot, please ask for any clarification needed. thanks in advance.