@tmomail.net not working

I have been battling this for over a year.  Sending from various email accounts no longer work while others work.  @gmail.com, @hotmail.com,. @aol.com, @yahoo.com, @edu.com, @outlook.com.  This is going to my phone number. I can send from my phone just fine.  It is maddening.  What I see in my email "Your message couldn't be delivered. Despite repeated attempts to contact the recipient's email system it didn't respond." I also have texts from American Messaging and so far those still work (what my company uses for alert pages).  I gave up working with TMO support.  Supposedly it was escalated to some higher tier support but I never was contacted and Each time I contact them I have to start the whole troubleshooting process\discussion over. No matter if I told them this is the 100th time I have called.