Email to SMS Problems

I run a small Boy Scout Troop communication list.  I send out weekly email to sms reminders about activities.  Tmobile has blocked the email address I use.  I just got the following from sixteen (16) of my Tmobile users:



The response from the remote server was:

550 permanent failure for one or more recipients (


Final-Recipient: rfc822;

Action: failed

Status: 5.0.0

Remote-MTA: dns; (, the server
  for the domain
Diagnostic-Code: smtp; 550 permanent failure for one or more recipients (
Last-Attempt-Date: Tue, 11 Apr 2017 16:18:25 -0700 (PDT)



I checked with barracuda and they said I wasn't on their list, it must be on Tmobile's end

How do I get unblocked?


Best answer by tmo_marissa 19 April 2017, 18:18

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15 replies

E-mail to SMS is not considered very reliable. Is there a reason you use that rather than just e-mail?

14 - 15 year old kids don't check emails.  Group Texts are annoying. It is a fast and easy way to remind kids/parents what is going on with the Scout group that day/week.

It should be reliable.  It worked perfectly, until it was blocked by Tmobile.  All of the other service providers work perfectly.

Have you tried sending the e-mails one-at-a-time? T-Mobile is pretty aggressive about blocking SPAM and your e-mail's might have been flagged as such. Also, T-Mobile used to market their E-Mail-to-text tools. They discontinued them and only left the e-mail-to-SMS system in place without much support.

Userlevel 3

Hey @meadowsvarsity2000‌!  I think email to messaging is definitely a creative way to get a kid's attention - we want you to be able to use it.  Can you take a look at this thread: Text Message via Email and let me know if the suggestions from our engineer to force the message to convert to MMS are helpful? 

- Marissa

Userlevel 3

Happy Sunday, @meadowsvarsity2000‌!  I just wanted to stop by and see if you'd had a chance to look over that link or test any of the suggested methods to force the message to deliver over MMS.  How is everything going with your troop communications?

- Marissa

The issue is with T-Mobile and not Barracuda Networks.  I own a text marketing company that sends over 500,000 messages per day in which 100,000 alone are to T-Mobile subscribers. Forcing MMS by creating a message longer than 160, setting the content type to "html/plain" or even including an image will only prevent T-Mobile from "repackaging" your message to a temp short-code for delivery. This will not stop the 550 permanent error. Even if you have the correct SPF, DKIM, PTR (rDNS), SMTP Banner and any extra SMTP IP A records set to your mail server, the failure will continue. What is happening is T-Mobile's SPAM filter (not Barracuda) is seeing your messages as SPAM, if you are using the same subject every time and delivering to just 100 subscribers every 24 hours, you can be blocked permanently.  We resolved our issue by purchasing another TLD (domain) and sending mail through that channel. It was actually a good move because all of our clients access the platform/website through "" but all the mail is delivered through "" but both domains have the same hostname/mail server name of Hope this helps anyone who has had issues. Remember to use MXToolBox or DNS Stuff to check your IPs, mail server, domain, blacklist, SPF, DKIM, PTR and other records for accuracy.  For those sending a lot of messages per day it's advised you use round-robin IP sending if you have more than 1 IP on your server as well as configuring EXIM in all areas on your server both GUI and command.


t mo support told me that t mobile will be getting away from all Email to SMS as it is " OLD TECH"

Was a way to get this working found?  I'm also trying to send text messages for a Scouting event and text messages to my own phone number are blocked.  My code is working fine for texting a Verizon user.

I found out it was blocking my messages when it detects the same subject line every time you send your bulk messages. I guess it thinks its a spam when you send messages to many users with the same subject line.  I send my messages every week, so I change the subject line every week.  Just change the subject line after every bulk message you send. 

It is odd that TMobile does not support subscriber whitelisting the source of email to SMS messages.  If your generic SPAM filters false positive identify my messages as SPAM, I should be able to control what I'd like to receive.

TMobile is now blocking my video surveillance notifications.  This is simply denial of service.

Fix it!

I think there might be/have been an outage in this system today. I have a forwarder set up from my Gmail to my text email for some important subjects. Today I have received bounces on those forwarders.

Mine is being blocked as well.

I've been in touch with Barracuda Networks and the problem is a malformed date/device ID in the E-Mail. I CAN ask/request T-Mobile to white list my device, as it HAS works for the last year or so I've been with them (bad  choice in carriers), but I'm quite sure they'd have absolutely no idea how to do that.

This started NOT working about 3 months ago.

I’m having a similar issue. When my job sends out mass emails about shifts, I never receive them at all. I spoke with a Tmobile Expert and I got a ticket number to resolve the issue . The issue is still continuing.

You will need to cal lthem and tell to allow short codes on your number.  It seems like every 6-18 months they disable that feature and you have to have it renabled- Takes 2 minutes.  The issue is you don’t know when they are going to disable it.


I have been attempting to get this resolved with Customer Service for over a month now with no results.

At work, my Outlook email is the only way I can text my family, email to text. It does not work.

It Will work if I message someone on another carrier such as Verizon. It will also work if I use my Gmail account, which I don't have access to at work.

Anyone have an idea why I can't send an sms to the other phones on my plan from Outlook?