I have a system that sends notifications to volunteer firefighters when they are called out for an emergency (a fire, car accident, whatever).
The system uses the 10 digit number plus @VTEXT.com -- It has worked fairly well since 2005.
Right now, almost every message is being rejected at least once by "vrz-sms.mx.a.cloudfilter.net" It simply isn't responding at all,.
If you contact me, I can provide the IP that our server uses to send the messages -- but I don't want to post that publically.
I can tell you that the sending server has proper SPF records and reverse dns configured, and has no trouble sending to other carriers like AT&T and TMobile.
