This is the first time I have come up against this, our email started to go a little wierd so I have had a look at the system:
SBS 2003, Trend Micro CSM, ORF 4.1 Spam Fitler, ISA 2004, Exchange 2003
Well ultimately realised we were having a real issue with ISA 2004, and after many weeks trying to find a solution I uninstalled ISA and then re-installed with service packs.
I have put the clients back on network, even replaced a router (with same make and model) however I am unable to receive email from specific sites although I can send to all of them. I Looked at everything, Trend, Spam filters, anti-virus, and all I can come up with is that either exchange is not forwarding the email on or somehow ISA 2004 is not allowing them through, though quite how it could do this is a mystery. Does anybody have any ideas, as I am stratching my head a little on this.
