Hi Petri
Thanks for your posting. Well, I agree - it's "something" with the firewall... but: We didn't change anything that has to do with the firewall (for example OS patches). We just installed Exchange 2007 Service Pack 3 and the Update Rollup 1. In my point of view it's strange that we have to change something in the firewall configuration after installing Update Rollup 1 for Exchange 2007 Service Pack 3 without any hints in the documentation - it smells like a bug with the Update Rollup 1 for Exchange 2007 Service Pack 3… So, we just waiting for an official statement of Microsoft and maybe for Update Rollup 2 for Exchange 2007 Service Pack 3 ;-) Should be released in December 2010...
Cheers,
Smiliman