E-mail to SMS being blocked due to suspected SPAM

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I am having the same problem.  We are an alarm company where our alarm panels send out email-to-SMS messages to our customers.  T-Mobile is now blocking 550 our emails.  We need to get our domain white listed as well.  I opened a support ticket, # 25596751, today by phone, but they really didn't seem to understand my problem.  I'm really hoping to get white listed as our customers with T-Mobile can't receive any alarm notifications right now.  All other carriers receive the messages without any problem.


Hi srickar,

I have the same problem as everyone else. I have emails of shopping deals from a website ( that gets sent to my gmail. I have a gmail rule that forwards these emails as SMS messages to me at But recently, the messages have not been getting sent to my phone and I get an error email from Gmail, pasted below. Any help is much appreciated. Thanks.

Message blocked

Your message to has been blocked. See technical details below for more information.

The response from the remote server was:

550 permanent failure for one or more recipients ( rejecting banned content)

Hello! We are having the same issue and could use some help with this. I was able to receive email to SMS on my tmobile device until just recently. I was testing a new service we intend to provide to our customers as we have an online auction site and customers would like to sign up for a outbid notification. Please note that they have to sign up for this service. We can send to ATT and Verizon and other carriers but get this bounce back from Tmobile.

The email is coming from an

    host []

    SMTP error from remote mail server after end of data:

    550 permanent failure for one or more recipients ( rejecting banned content
We will try changing the from / sender email and see if that helps - if not what do we need to do to get our domain white listed?

Thanks, @srickar.  Is there any way that we could have a particular address whitelisted so that texts with URLs are not flagged?


Thanks @srickar​. I believe it worked. I just used test2 instead of test 😀.

For anyone else wondering your sender has to be the same as the true sending address. email to rejected for banned content

"IMPACT: Customers may be unable to receive messages to messages to their address. To help aid the attack against SPAM, T-Mobile is now blocking traffic where the sending Domain is altered from the true sending address: IE, when the domain is actually is senders will receive a 550 bounceback error . To correct this issue, Senders will need to revert their sending address to their actual email address. For assistance, direct customers to the sending party, and sending parties to their domain customer support. this service is functioning properly."

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Hi @jpipvideo

I found the message based on the power of * search. 😊

You have an empty "Envelope From:" field which is a requirement for SMTP acceptance.

Please configure the sending server to have this and it will pass.

One more item to note, you have an email address with test@. That is currently not allowed because of the generic nature due to a spam storm right now posing as officially titled user names. (test@, admin@, webmaster@, postmaster@, administrator@, etc).

Hi @srickar

I have a similar situation but its a bit different. We use an smtp Client to connect to a gmail account that sends the email.

For some reason the manual email doesn't get blocked but the email through the smtp client does.

I tried this from another smtp client on another pc as well and was still getting blocked.

Can you tell me what exactly is the banned content? If anyone else has any ideas please let me know.

I black out some parts for privacy concerns but I can dm you the full details.

Hi @srickar. On our Inbox back and forth, you quickly unblocked Mindspring, and I think you took off. I wrote back quickly we were using SendGrid. When you get this, can you check back with us (even if it is next week at this point).

@srickar​ I just checked, and they are going through now.  Thank you so much unfortunately I'm stuck with generic email names Info, messages, accounting etc.

Thanks again.

Hi @srickar​.

Did you see my post above? I saw you try to 'connect' and I accepted, but I see no response above or in my Inbox. (Was it something I said, as opposed to others?)

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Just informing everyone that I will be out of office October 24th and 25th and will have limited ability to answer messages. I shall return on Monday Oct. 28th. And of course you may always contact T-Mobile TEXperts at 611 and submit a ticket for if you are experiencing issues with email delivery. Thanks.

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Did you check today? They are passing as I had made some changes yesterday 10/22 around 1230pm CDT. Please note that email could be blocked again due to matching with spam activity that's ongoing.

Reason was due to spam storm that's also using info@. It would be best to avoid using generic usernames that match with spam activity. Examples would be info@, postmaster@, admin@, test@, etc which are too generic but used by spammers which will cause your traffic to get lumped into same category. Unfortunately, spam attacks are heavy right now and can result in false positive blocking. Thanks for your understanding.

Hello @srickar​​  I seem to be having the same problem as others. It seems like it started Friday evening, and I've checked that we are passing SPF, DMARC and DKIM checks in the headers. It's only happening with and (which I believe is an MVNO through you guys) no problems through att, verizon, sprint etc.

Created Date:

10/22/2019 3:19:54 PM

Sender Address:

Recipient Address:


Your Messages

Error Details

Reported error:

550 5.7.350 Remote server returned message detected as spam -> 550 permanent failure for one or more recipients ( rejecting banned content)

DSN generated by:

Remote server:

Any help you can give is greatly appreciated.

Thank you, srickar!  That did the trick.

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If possible, please edit/remove identifying information in your cut and paste.

The appointment reminders are passing just messages that discuss Facebook. I checked, and the reason why this is blocking is a facebook URL is pasted in the message body. This type of block is necessary because spammers are sending out similar facebook spam containing adult content. If you could please remove the facebook footer from messages they will also start passing.

Thank you @srickar for your reply.

We generate appointment confirmations to clients a day before their

appointment.  Our email address is @colorboxsalon. Here is

the response I am getting when emailing to a T-Mobile client:

This message was created automatically by mail delivery software. A

message that you sent could not be delivered to one or more of its

recipients. This is a permanent error. The following address(es) failed: SMTP error from remote mail server after end of

data: host : 550

permanent failure for one or more recipients (

rejecting banned content)

@srickar, let me know if you need the sending domain, or the phone numbers that were sent to.

@srickar​, I am having the same problem. WE were successfully sending emails (domain authenticated) yesterday from our field services devices to TMobile numbers. This morning, they seemed to be blocked. What can we do?

From our email provider SendGrid:

Received by   




2019/10/23 10:17am UTC-04:00

The server blocked this message from being delivered. While we won't try to send this message again, we will attempt to send new messages to this address in the future.

You can view all addresses in your Blocks suppression group. Learn more.

Full response from the server:

550 permanent failure for one or more recipients (

We are getting a similar issue with our employees/your customers. Is there anything my company can do?

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Sorry cannot whitelist external senders. There is a spam outbreak that is using info@ so I cannot unblock at this time.

So, you're filtering on the info sender?  Is there a way to get whitelisted?  We're not sending content unless someone asks for it.

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generic reply envelopes such as info@, postmaster@, webmaster@, root@, sales@, are spam sources and are not permitted at this time.


Hi, just checking in again on this.  Is there someone at T-mobile I can get in touch with about whitelisting?

I'm getting this as well, can anyone help?

I actually have Walmart Family Plan via T-Mobile

SMTP error from remote server for TEXT command, host: ( reason: 550 permanent failure for one or more recipients (

54 rejecting banned content)


Hi,  you were able to help me a couple of months ago, but we just started seeing a block again.  Not sure why.  Here are the details of the message:

<>: host[] said: 550 permanent

    failure for one or more recipients ( rejecting

    banned content) (in reply to end of DATA command)

---------- Forwarded message ----------





Date: Fri, 18 Oct 2019 12:25:54 -0500 (CDT)


602-xxx-xxxx replied to Ad Code(RKTxxxx) with: 'Price ?'

This was the first bounce we got, but subsequent messages are bouncing as well.  Can you give me an idea of what could be causing the issue?  We haven't changed anything wrt to content sent.  maybe a rule change?  Any help is appreciated.  I can be reached at 877-848-4045.  Thanks