Blocked port 25? -- problem discovered, thanks!

Thanks for everyones help and good information. The problem has been discovered and a solution is pending.

NMSU peers with UNM, and we provide backup Internet routing for each other. UNM is in the process of adding Time Warner Telecom as a peer, and they are not advertising NMSU's routes correctly. The result is that all customers connected to Time Warner Telecom are using UNM as a transit to get to NMSU. UNM also has a filter on their border router to prevent access to unauthorized SMTP servers, and this affectively blocked the Time Warner Telecom to NMSU mail traffic.

I am presently working with the UNM engineers to fix this problem. I didn't see the Time Warner Telecom correlation in my traceroutes, because many of the places were multihomed, and the traffic from NMSU was taking a different ingress into their network.

It would seem that my email is broken, too. It would appear that I let my domain expire, and the email address I have on record with Network Solutions is not longer valid. bleah.. Too early in the morning to have to deal with this stuff.

Thanks again to all the NANOG members that helped me quickly diagnose this problem.