I have published an SMTP server which starts off working OK but then after a while it stops allowing inbound requests on port 25 and if I do a netstat -na port 25 doesn't show. The ISDN adapter is in the ISA server and it seems as if when ISA checks the publishing rule when it isn't connected to the ISP it can't see my external address and the rule fails. The only way to get it working again is to establish a connection and stop and start the firewall service (every 1/2 hour). Has anyone come across this or have a work around?
The ISA server is using an ISDN dial up adapter (receives a static ip address from the ISP) which is fine for publishing the SMTP server as the Exchange server forces a connection when sending mail and then issues the ETRN. The problem seems to be the same as the following: http://www.isaserver.org/ubb/Forum6/HTML/000003.html
I see! I checked out that thread and they identify something I've noticed too.
When you lose the dial-up connection and re-dial, the publishing rules don't seem to activate. If you check the Alerts node, you'll notice an error that says something about a resource allocation failure, and you'll see a little bit later that there has been a failure in a server publishing rule.
Why does this happen? Don't know - probably will be fixed in ISA Server SP1.
However, you can kick start the rule by disabling it and then re-enabling it.
If you get SMTP and POP3 publishing failures when the connection has *not* been dropped, try disabling the POP3 and SMTP filters.