I am running NIS 2009 v16.5.0.135. My can't get my email, only from Verizon.net, with NIS having inbound email scanning turned on.
I have run tests with inbound scanning on and off, I also checked to see if this had anything to do with Verizon switching to port 587, and even tried a custom firewall rule for that port. But, just turning inbound scanning on and off blocks connection to the POP3 inbound email.
OK, forget the port 587 issue, it was just 'give that a shot' attempt to see of 587 was only an outbound email change with Verizon. (although NIS will have to add that for outbound scanning in a future update)
But, the problem still persists. With inbound scanning, I cannot receive email from Verzion.net (on incoming.verizon.net mail server). Unchecking the inbound scanning setting works fine.
Could you tell us the email client that you are using? Perhaps, that will help us get more information about the root cause of the problem that you are facing.
Please do a Help-About in Outlook 2003 and tell us what information is displayed about the revision (build) level.
BTW - not that this is going to help resolve your particular problem, but have you applied all Outlook 2003 updates, via windows Update? If not, it would be best to do that, first.
With inbound scanning enabled, do you get any indications that your mail is being scanned? Also, if you check the Security History, does it say if any mails were scanned, and what was the result?