E-mail to SMS being blocked due to suspected SPAM

I work for a trucking company, and we use e-mail to SMS to send out dispatch messages to our drivers for load information. Drivers can then reply to those messages to have conversations with dispatchers who operate via e-mail.

This has been working for years; however, as of 3/26/2018, it seems our entire domain has been blocked by T-Mobile servers. E-mails sent to are rejected with 550 errors. I have tried sending as plain text, e-mail, short, long, with picture, and just about every way I can think of, but it's always blocked. Messages sent to all other mobile carriers are still going through just fine.

I have tried calling support, but no lower-level techs seem to even understand what E-mail to SMS is, and they just exhaustively try things that are specific to one individual phone. They supposedly escalate the issue, but we never hear back. I am desperately searching for someone within T-Mobile who can actually tell me why my domain is suddenly being blocked. This functionality is critical for our drivers to do their jobs; I'd prefer my answer to those drivers not be "sorry, find another carrier" as they keep asking us why their messages are failing while all the non T-Mobile users are moving along just fine.

@srickar​ - I've seen where you've been super helpful to some people; is there any chance you could help us out, too? I can PM you specifics.


Best answer by tmo_chris 5 November 2019, 00:21

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238 replies

Userlevel 4

Hey, @ffit37129​!

I've seen an uptick in situations such as yours. It's possible that your company's domain just needs to be whitelisted. While I don't have the answers to why the sudden change, there is a ticket that can be filed. I know you've already worked with our tech support a few times with no luck.  Do you happen to know if a ticket was previously filed?

Yes, I do have an existing ticket. The number is 19367035. Thanks for your help!

Userlevel 4

Thanks for the handy info, @ffit37129​! I just sent a private message your way to provide more info. You can check your inbox here.

Thanks for that info, but that did not work. We have verified our SPF policy on the outgoing mail server is valid and even tried routing through a totally different server, but we are still being blocked and have no idea why. I have not heard back from tech support.

Just to clarify, I can send the exact same message to my personal gmail account, and the gmail e-mail headers clearly state that SPF passes and that the sender is designated as permitted.

Userlevel 4

Thanks for getting back to me. It sounds like we need to whitelist the domain. The only way to do this is via tech support or T-Force (Facebook/Twitter) and you'll need to refer them to doc# 433442 on steps with how to file the ticket.

Userlevel 2

If yours is a business account - you should have a rep to directly deal with.

Thanks, but it's not a business account - these are messages being sent to personal devices.

Userlevel 3
Badge +4

Hi @ffit37129​ are the message still blocking? I dont always check this forum, but follow me and I can follow back so that you can send me details. For faster support, f its a public domain, just type it here and put a space between the domain(dot).com and I will look for blocked content and get it corrected. Thanks!

@srickar​ - I'm also having issues with sending messages to T-Mobile phones via the e-mail to SMS gateway.  My messages are getting a 550 - permanent failure.  I noticed that you had recommended that others with the same problem follow you and communicate directly, so I went ahead and did that.  If you could approve my Follow request, I'll send you the details directly. Thanks!

Other info...

It appears that my SPF is set up correctly.

I can send to other mobile services (AT&T, Verizon, etc.)

Hi @srickar​ - it took a few weeks, but we finally got in touch with someone high enough in the tech chain who whitelisted us. Unfortunately, no one was able to really explain why it happened or give any real assurances that it wouldn't randomly happen again. Thanks, though.

We did finally get this resolved. A few key points:

  • @ @tmo_amanda was correct - we needed to get whitelisted. However, finding the right people for this was nearly impossible as it seems no one in tech support has any clue what that means, and the doc number was apparently not helpful.
  • I tried calling tech support as well as opening a ticket via twitter. Both of them directed me back to support here on this forum, which was not useful.
  • We were asked several times if we had a business account and had to explain repeatedly that these are messages going out to people's personal devices, so a business account wouldn't help us even if we had one.
  • Our CIO finally managed to contact T-Mobile people through LinkedIn and other channels who finally connected us to someone high enough in the support chain who unblocked us. We never got any information on why we were suddenly blocked, so it seems possible it could happen again.
  • I'm glad it's working for us again, but my suggestion is that if you're going to have such aggressive blocking, you should really have a more clear path for people to get whitelisted.
Userlevel 3
Badge +4

Okay thanks for letting me know it is working.

SMTP email requires spam filtering, which is globally and dynamically subjected to filter changes based on global spam trends from top spam reputation lists and content phrase databases. IP's and SMTP host reputation also plays a factor in pass/fail for email in addition to content.

Grammar, alphanumeric phrases, volume, and CAPS LOCK contribute to spam scoring properties.  Email is intended for casual quantity and over-extending volumetric limits may result in blocking. These are industry standard methods to thwart spam attacks that have increased in the last decade.

@tmo_amanda and @srickar​ - It looks like @ffit37129​ was able to get this issue fixed for his domain, which is very encouraging!  Who do I need to get in touch with to get the blocking issue resolved for my domain?  Sounds like I need to get whitelisted.  @ffit37129​ - if you can direct message me the info of whoever was finally able to help you, I would be eternally grateful.

Userlevel 3
Badge +4

I can assist you but we don't typically whitelist domains outright without verifying the problem. Can you please submit a ticket via 611 about messaging? I can also check on my end, but would need to know the inbound address domain. Thanks.

@srickar - I'm not a T-Mobile customer, but my domain sends messages to T-Mobile users who use my company's service.  I think that means that I can't submit a ticket via 611.  I'd be happy to send you the info directly if you are able to assist with verifying the problem.  I sent you a "Follow" request earlier today. Thanks! Our T-Mobile customers will be so excited once we get this resolved! Can't wait.

Userlevel 3
Badge +4

Okay thats fine too John. I followed you on inbox. If you follow me on inbox as well, send me the details and I will be happy to research. Thanks!

Userlevel 3
Badge +4

Just as an FYI to others, I reviewed the PM you sent and removed the block that was due to high volume. Please check out the PM and let me know if you see messages passing.

srickar, wanted to inquire on a similar possible block for another domain. I can PM or work on details here, if possible?    

Userlevel 3
Badge +4

Certainly. If its a unique domain and you feel comfortable sharing it here I can take a look and see why its blocking. Please dont share the full address here if you choose to do that, just the domain. If its or some mass domain, you'll need to follow me on inbox and send it there instead. Thanks!

Gotta say you're doing a phenomenal job with this. We use the SMS alerting to check MX uptime, and this is a public domain so:

Userlevel 3
Badge +4

Yikes there's a lot of traffic from that envelope where 99% are passing through just fine. I found 1 blocked message but it was due to 1-2 items.

In the header, the message is blocking because of ehlo domain containing .ru which is TLD for .Russia. We do not accept .RU TLD traffic because of the preponderance of spam originating from international sources. Secondly, there is a link in the footer. We do not accept links because of spammers using short URLs to send spam blasts.

If this is not your situation, please follow me via inbox, and I can take a look at specific recipient number. Thanks.

A follow was sent, I'll send further info to you via PM once you accept.    

Followed via inbox, this time the right way 😊

@ @srickar   I'm having the same problem with my company email.  Who do I contact to get the domain white listed?