Hi All. I have some users from another company who are visiting my company. The use outlook to access their mail. I think it is via RPC over https (ssl). When there are on my network they are unable to send messages but when the connect to an ISP directly they are able to send. I have a cisco 2821 as my internet router and an ASA5505 (8.0.5...i downgraded it from 8.2.3) as my firewall. I have not blocked anything from going out.
Of note is that when other users use window live configured for gmail....which uses tls they are unable to send emails with atachements. Regular emails go though no problem. Hotmail can send atachments without a problem (there is no encrytion there).
I have narrowed the issue down to how the firewall treats esmtp or tls traffic passing though it. I have already diabled inspect esmtp on the firewall. Do you know what else i could try?