Nagios Support Forum

Appaernly the issue was another computer on our domain caught the crypto virus and caused our public IP to blacklisted. A NIGHTMARE, but we have removed the infection and requested our IP to be unblacklisted.

Correction, that was not the issue.
I have verified the carrier listing for AT&T is %number%@txt.att.net, and I have placed a phone number in the user account and pointed it at AT&T. The emails come in locally and externally, but the carriers do not. I have tried running the following from the command line:
echo "test" | mail [email protected]
I recieved nothing. *Phone number has been changed to protect privacy* I can connect on port 25 via telnet to mx.txt.att.net
I have no clue where to look now.

Do you see the SMS messages logged as sent or queued for delivery in /var/log/maillog when you try to send them?

They were queued for delivery, however they are now going through. Apparently the "your request may take an hour or two message" listed on RBL's and CBL's is more like 6 or 7 hours.

This is awfully long. You need to contact ATT and find out why this is happening. I would also check the message preferences on the account. Sometimes, email-to-text messages could be blocked, there are some limitations on the number of characters, etc.

It took a while, but they finally un-blacklisted the public IP / domain. This issue is resolved.