If you suddenly stop receiving text messages from a service that sends you messages from email - email to text messages, check any text spam blocking software you might have on your phone.
I'm a complete stack web developer and my server sends my clients emails that are converted to texts in this send to format email@example.com
My server started receiving emails back rejected by Barracuda which is a spam blocking software.
T-Mobile assured me they don't use Barracuda spam blocking software.
I disabled Norton Mobile app on my phone-hand set-device and subsequently sent email to texts came through to my phone.
So, if you are having similar problem, it's not T-Mobile causing it. It's spam blocking software on your device that needs attention.
-- just in case you are scratching your head over a similar problem.
Manage your T-Mobile account