My ISP blocks port 25. I'm having a hell of a time getting my internal exchange server to deliver mail on a different port. I have configured my send connector for port 587 (among others for testing) but mail sent to the Internet (gmail / yahoo / other) simply will not deliver. I see the connection establish on my TMG firewall on the alternate port, but the messages just stay in the exchange queue with the error: Remote Server at gmail.com (2a00:1450:4013:c01::1a) returned '441 4.4.1 Error encountered while communicating with primary target IP address: "Failed to connect. Winsock error code: 10051, Win32 error code: 10051." Attempted failover to alternate host, but that did not succeed.
I don't understand why I can't get mail to deliver? Maybe it's my DNS, although it seems to be working fine. I have a split-DNS, no other systems have issues. I'm also seeing the connection resolve on my TMG logs. Is mail in fact actually being delivered on port 587 and maybe gmail / yahoo isn't allowing it through? I'd like to configure this on my end, but more than likely would be solved with a SmartHost provided by my registrar.
-SK