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natederry's profile

New Member

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2 Messages

Sunday, March 13th, 2022 9:05 PM

SMTP Server to SMS Messaging

We are a small video surveillance company and we have a SMTP server that used to send SMS messages to recipients to alert them of motion detection, or door opened or other sorts of messages. This has worked flawlessly for the last 10 years. Recently (About 3 months), the messages are now bouncing back to the mail server. I have checked our SMTP IP address against all of the blacklists and it is not listed on any blacklists. The message we get back from ATT is this:

Remote Server returned: '550 5.2.0 - TTTrnA7Q12cEiTTTrnbzN4 - Internal error'

Which when investigated, appears to be an authentication issue - but there is no way to authenticate on ATT's mail server from another SMTP server.

Is there a way to fix this issue? It is almost as if ATT has our IP blacklisted and if there is a way to get that removed, our clients would be exstactic.

Thank you.

Community Support

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231.3K Messages

2 years ago

Hello @natederry, we understand your concern with the error messages your company is receiving and we want to help. 

 

To better assist, we'd like to confirm additional details with you:

  • Is this error continuing with multiple customers or just a a few times?
  • Is your company currently using AT&T services so that we're able to continue to further investigate?

Feel free to reach back out and let us know so that we're able to further assist and help with your inquiries. 

 

Thank you!

 

Lynn, AT&T Community Specialist

New Member

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2 Messages

2 years ago

It is occurring with ATT customers only and it is every time a message is sent.

As a test, I send a message from the mail server directly to my, or my wife's, own ATT cell phone, and the message fails to deliver. Have tried the @mms.att.net as well as @txt.att.net addresses and neither work.

Again, we have been using this service for the last 10+ years and it is only recently (past 3-4 months) that it has stopped working.

I can send email to text messages from my hotmail account, comcast account, and any other account other than our smtp server, which emails hundreds of people a month in this manner.

Thanks for following up on this issue,

Nate Derry

New Member

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3 Messages

1 year ago

Did you ever get this resolved? I am having this same issue over the last few days

New Member

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19 Messages

1 year ago

Reason: [{LED=450 4.2.0 <email> - ZmzgpsdQ8Y8HhZmzhpm4bF - Service temporarily unavailable};{MSG=};{FQDN=mx3a.txt.att.net};{IP=166.216.149.129};{LRT=3/8/2023 6:09:43 AM}]. OutboundProxyTargetIP: 166.216.149.129. OutboundProxyTargetHostName: mx3a.txt.att.net

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