I recently experienced an issue where my Cisco ASA 5510 just magically stopped forwarding SMTP traffic from outside my organization. I have never used a ASA before. My OWA access works and internal mail still flows. IT is when someone outside the organization attempts to email someone here at my company, the email either does not make it and they get an errror message or it is very extremely slow in getting here.
I have attached a copy of the running config from my ASA.