Symptom:
Mail is not sent using SBC Internet Services. Running mailq shows queued mail with the message "Deferred: connection timed out with ...". Telneting to port 25 of an external SMTP server hangs indefinitely.
Solution:
SBC Internet Services is blocking port 25. You can opt out of port 25 blocking by filling out the form found here: http://help.sbcglobal.net/article.php?item=4640.
You will need to login to your SBC Internet Services account.