email to rejected for banned content

  • 15 October 2015
  • 71 replies

I've used for a couple of years.  Sometime between Sep 30 and Oct 3 the servers {dal or chi} started rejecting messages from my mail server with the message: 544 rejecting banned content.

I've done some testing:

  • What works:
    • If I test with a gmail account, the message is delivered to my cell phone.
    • My mail server can deliver the same message to <phone> to a friend's phone.
  • What generates the same error:
    •    Prefixing my phone number with a "1".
    •    Using the T-Mobile phone number of my data device, my son's phone or my daughter's phone.
    •    Using a simple message with subject "test" and body "test" that has no content worthy of banning.


Would you say that the servers have effectively blocked my email server?  Has anyone else had

this issue and had it resolved?  Has anyone had their email server whitelisted?





Best answer by tmo_lauren 22 October 2015, 17:29

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71 replies

Userlevel 3

I took a look at known issues for this and found:


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.

ETR: No ETR - The service is functioning normally.

This sounds like what may be impacting you, so you may need to contact the sending domain directly!


Thanks for taking a look.  I have seen the issue you describe.

In my testing, I tried to set up an email alias, tmomail@myserver, on my server that would forward the email to  Then I sent an email from a account to tmomail@myserver. rejected the email and the mail delivery system of my server sent an " Undelivered Mail Returned to Sender" bounce notice to my gmail account.  From the bounce notice:

<> (expanded from <tmomail@myserver>): host[] said: 550 Rejecting for Sender    Policy Framework (in reply to RCPT TO command).

This is quite right.  Mail is being delivered for a sender with a gmail address by a server not authorized in the SPF record to deliver email for gmail.

Anyway, error 554 "banned content" is different from what you found.

Today T-Mobile has made some progress.  My mail server doesn't have a typical name like: or  If I understand correctly, the name of my mail server was being caught by a regular expression in the spam filter and blocked.  Hey, really, it was as innocuous as

I said "some progress" because earlier today, my test messages were not banned, but no SMS messages were delivered to my cell phone (using both my server and gmail's server). 

However, just now, I tried again and within 4 seconds of sending an email to the message was delivered to my cell phone.

So the problem is fixed.

Thanks T-Mobile.

Userlevel 3

I'll keep an eye out and research for other possibilities and report back if I find anything better fitting your situation!


Hi Lauren,

I work at a university and our students can sign up to receive SMS notifications from our Learning Management System when certain things happen in their courses. Over the past month and a half we've noticed getting bounces from primarily T-Mobile users with the message:

<>: host[] said:

    550 Rejecting for Sender Policy Framework (in reply to RCPT TO command)

I checked with one of the students and she was getting the messages as recently as last weekend when she upgraded from an iPhone 5s to an iPhone 6s. Would the sms messages be routed/received differently depending on the device?

I've also been exchanging emails with our LMS vendor on the issue and they recommended I direct the students to T-Mobile, but your post indicates the student should be contacting the university, who would then need to contact the DNS host (our vendor).




We are also having problems with sending to The messages are not being blocked with the 550 error. Sometimes we have to try sending the message multiple times before it is delivered. Users using other carriers (Verizon, Sprint, AT&T, Republic Wireless) have no problems receiving messages.

Userlevel 3
Badge +4

I happened to notice this posting. I am the spam admin for services and would like to assist.

Sender Policy Framework 550 status message is part of spam validation screening. "550" is part of a long list of SMTP status codes to help diagnose connection issues.  Mail relays connecting to DNS and MX (mail) records must match or be authorized on behalf of another domain. The mismatch can occur in the registered domain or the shared ISP network connection.

This very simple FAQ provides a very high level understanding of SPF 550

SPF: FAQ/What it does

This can occur when a company or university has an affiliate brand or satellite university, attempting to send email on behalf of the parent company. The authorized administrator for the parent company or university, needs to update DNS and MX records permitting all authorized affiliate mail relays to send on behalf of the parent mail server. Otherwise, the assumed SAFE policy is to "reject" the mail until the record is corrected. SPF is a global standard policy and can be strictly enforced or relaxed to accommodate spam control. Most mail administrators already maintain current MX and DNS records to accommodate for all global mail hosts they may need to communicate with, but sometimes there are exceptions or missed segments as companies grow or change hands.

With that said, SPF 550 response codes are intentionally sent back to the message originator to alert the sending party their DNS/MX host records are not up-to-date or mismatched.  SPF prevents any rogue entity from spoofing the reply to: envelope on the received outgoing message sender.

T-Mobile cannot update DNS and MX records on behalf of sending mail servers, only the authorized administrator can perform this task.

Thank you for your reply. Our server admins updated our SPF record last week to included the sending parties domain, but are still getting returned. How long would you expect it should take for the SPF update to propagate to your system?

We don't get 550 returns from other major carriers, would they be doing something different?


Userlevel 3
Badge +4

550 should clear in a matter of hours. Without knowing your domain, I can't determine the full reason for the denial other than SPF is not permitting the mail relay to send on behalf of the domain. Please submit a ticket to T-Mobile customer care regarding blocked emails to and we can take a look. It would be helpful to provide the SMTP logs so I can see the IP and hosts associated in the transaction logs.


where would i file a ticket? I've searched and searched, but cannot for the life of me find the page that allows me to file a ticket and submit my postfix/wireshark logs.

Userlevel 2

You'd Community-2153‌ over the phone or your best bet would be to reach out to our T-Force team via our Facebook page or Twitter (links are on the Contact Us page). You should be able to paste the relevant parts of the log in to the messages once making contact or they can likely give you a place to send them to them (or if you have them in Dropbox or Pastebin and can provide the link).

Tickets are created by our frontline teams and they'd have a series of troubleshooting/investigative steps they'd be required to do before creating a ticket and forwarding it up. Think of them as Level 1 support and you'd need to get to level 2/3 via the ticket.

Why isn't there an email address to send to? Why require users to have a twitter or facebook account in order to submit an issue electronically? This is one of the dumbest policies I've ever encountered, it makes me absolutely furious that t-mobile thinks this is acceptable.

Shame on you!

Userlevel 3


As of now T-Mobile offers full support on FB and Twitter, as well as over the phone, as well as billing support and basic troubleshooting through live chat. For an issue of this nature requiring a ticket, we would need to make sure you get to the proper tiers of technical support which are currently available either through social media or over the phone.

We understand not everyone wants to make a call which is why online options have been added, but we will certainly get your feedback passed along regarding e-mail.


I am having the same issue. I have my google calendar send updates to my gmail and I have it filter to forward to as an additional reminder. This has not been an issue till recently....any suggestions...below is what it looks like...

To: @magenta5565064

Delivery to the following recipient failed permanently:

Technical details of permanent failure:

Google tried to deliver your message, but it was rejected by the server for the recipient domain by [***.***.***.***].

The error that the other server returned was:

554 rejecting banned content

It is obviously not spam...Please help!!!


Userlevel 3
Badge +4


554 banned content likely covers a large swath of keyword content in the message body. In the past quarter, T-Mobile has been under heavy spam attack from lottery/inheritance gmail spammers registering hundreds of gmail addresses and sending 1,000 spam messages per each email account in attempt to circumvent detection. They are inserting different reply addresses in the body of the message which drives up the block score. Since we cannot outright block all gmail traffic without impacting legitimate content, we have to resort to other expressions and limitations that may cause false positive blocking.

Please try to a.) draft a new email and send it to your Was it received?  b.) manually forward a message to your Was it received?  Gmail forwarding inserts a "caf_" in the reply to: email address in the message properties but can cause issues with trusted forwarding. It could be prior headers in the message body that are triggering the block.

Without knowing your mobile # or true email address, there would be no immediate way for me to search and distinguish your specific content in the millions of gmail messages in quarantine. Please submit a ticket to T-Mobile care that includes these details (please don't share them here).


I manage a mail server for real geeks and we send a lot of messages on behalf of our customers to their SMS gateway addresses.

Recently, all of our messages have started bouncing back with 554 rejecting banned content

Is there any way you could whitelist our mail server's IP address?  I know you are making some changes to fight spam, but it is hurting our clients who want to get notified of new leads coming into their websites.

I would post the logs on here but they have private phone numbers in them.  I can email them to you if you would like, along with samples of what our text notifications we send through the SMS gateway look like.

Our mail server IP address:  **.***.*.***

Userlevel 6
Badge +15

Hey @jcw1‌ I checked on this and you're gonna want to run this by our T-Force team. This would need to be escalated to our network engineers and T-Force has the ability to do this. You can send them a message through the Facebook, Twitter, or Google+ links below. They can file a trouble ticket for you and have this looked into further.

@tmo_mike_c, does that apply to my question as well?

Userlevel 6
Badge +15

Yes it does @kevin1024. It's worth it to have this looked into further so when you get a ticket filed for this, it'll help.

Userlevel 3
Badge +4

If this is regarding Gmail, I have made additional adjustments for gmail based messages. Can you please retest? If it's still rejecting, please submit a ticket to T-mobile T-Force. They can forward the private information to me.

OK, thanks tmo_mike_c.  I contacted support using twitter and they written an internal email to the "National Sales Engineering team".  They said there is no ticket number, just the email.

Here's the chat transcript in case you can provide some feedback with other info I should give them to speed it along:

Hi I manage a mail server for  and we send a lot of messages on behalf of our customers to their SMS gateway addresses. Recently, all of our messages have started bouncing back with 554 rejecting banned content. Is there any way you could whitelist our mail server's IP address?  I know you are making some changes to fight spam, but it is hurting our clients who want to get notified of new leads coming into their websites.  Our mail server IP address:  x.x.x.x

T-Mobile USA

Hey thank you so much for taking time out of your day to reach out to us! Oh no! Our fight against SPAM should not impact your customers. We definitely need to get our engineers involved ASAP so we can get you back up and running! So we can provide a timely resolution, please fill out our short form and we will get started 😊  *JacintaJ


Thanks.  I don't actually have a T-Mobile phone.  We have thousands of customers with T-Mobile phones though.  It looks like I need a T-Mobile phone to fill out that form.

T-Mobile USA

Thank you for the clarification and your effort Kevin! What we could do is reach out to our National Sales Engineering team via email to resolve your issue and then set a follow-up with you and reach back out to you here to provide you an update. This may take a few days to get a response or resolution back, would that work for you?  *DarwinM


Hmm, that would not be ideal since our customers are having trouble working without their text notifications.  I asked in a forum thread here: …  and was told that T-Force (is that you?) can escalate to the network engineering team.  Also tmo_mike_c over in that thread indicated that he might be able to help out with the ticket.

T-Mobile USA

That's us! That's correct! As I mentioned, we can reach out to the engineering team however, this is via email. We'll submit the trouble ticket and as much detailed information as possible to our engineering team. Just to set the expectation, it can take a few days to resolve. If this is an SMS delivery issue from a short code, the other option is if those clients contact us, we do have the option of making short codes aren't blocked on their line. I hope this helps Kevin. I truly would like to push a button and speed this up for you.  *DarwinM


Ok let’s get the ball rolling then!  It’s not from a short code, it’s using the email to SMS gateway.

1h 1 hour ago

T-Mobile USA

Ah, thank you for the better understanding Kevin. We're right on it! Are you able to provide a good contact number and email, as well as a good time to reach you just in case they're able to reach you directly?  *DarwinM


Certainly! @leewillcox xxx-xxx-xxxx I'm based in x, so anytime x works for me

T-Mobile USA

Great. Do you have the possibility of sending us a screenshot of the error message you're being provided or is that an error message on the client's devices?  *DarwinM

57m 50 minutes ago

Kevin McCarthy

I can send you a screenshot of my error logs I'm getting from my mail server. (screenshot attached)

T-Mobile USA

Thank you so much for that. What I will do is create a follow up and hope that we can get a resolution for you within 72 business hours! I'll be reaching back out to you by Monday. T-Force is here 24/7 should you need any other assistance. I appreciate your effort and patience on this matter!  *DarwinM

Kevin McCarthy

OK thanks.  Can you give me a ticket number?  I would like to update srickar and tmo_mike_c in the support forum thread.

T-Mobile USA

Thanks for staying engaged Kevin.  Presently, the email is serving as a ticket number and will receive a response from them within the next 72 hours.  Now we do have a follow up with you for this coming Monday to give you more detail info on those sms concerns.  We will have more information then.   *KimB

I've also recently been having issues. I have an outlook rule setup to send me a text notification when I receive emails from certain people. Somewhere about mid Jan 2017, this stopped.

In my testing I have found a few things.

If I send myself an email with a signature, I won't receive the text message. If signatures are turned off, no signature is included, and I'll get the text just fine.

In one test, Remote Server returned '< #5.0.0 smtp; 550 permanent failure for one or more recipients ( rejecting banned content)>' was received.

This email also included a signature. Seems that something is filtering, or not understanding the info its receiving.

We are also having this issue.  Your requirement seem a little strict as there are many reasons for sending email through a legitimate email server like Amazons' Simple Email Service where we send texts from.  Can I ask you to at least consider large vendors that have already put in place a strict vetting process?  We have hundreds of users using T-mobile and I'd really like to have access to a Customer Service Representative.  What do I need to request support?

Here is a copy(minus sensitive stuff) of the email.  Perhaps there is another issue?

Reply-To: <>

From: <>

To: <>


Date: Tue, 21 Feb 2017 09:31:04 -0700

Message-ID: <>

MIME-Version: 1.0

Content-Type: text/plain;


Content-Transfer-Encoding: 7bit

X-Mailer: Microsoft Outlook 15.0

Thread-Index: AQGu4+u0SWwhVbgnEZ3ptaN7T1w22A==

It is not enough to have lived. We should be determined to live for


Here is the response:

Action: failed

Final-Recipient: rfc822;

Diagnostic-Code: smtp; 550 permanent failure for one or more recipients ( rejecting banned content)

Status: 5.3.0

first time here, apologies for n00b mistakes ahead of time.

We have Office365 at work, I use the OWA client (a Linux kinda guy 🙂.

I have it configured to SMS meeting notices to my mobile.

It started bouncing messages late last year, but not all of them.

example is below.  I checked our MX setup, and both mx1 and mx2

are there, so I don't know why it's rejecting this.  certainly don't know

why it's 75/25 reject/arrival.

any help appreciated, I'm getting a terrible reputation for missing meetings :-)

This is the Spam Firewall at

I'm sorry to inform you that the message below could not be delivered.

When delivery was attempted, the following error was returned.

<: host[] said: 550 permanent

    failure for one or more recipients (:blocked) (in

    reply to end of DATA command)

    [ Part 2: "Delivery error report" ]

Reporting-MTA: dns;

Arrival-Date: Thu,  2 Mar 2017 10:45:06 -0800 (PST)

Final-Recipient: rfc822;

Action: failed

Status: 5.0.0

Diagnostic-Code: X-Spam-Firewall; host[] said: 550 permanent

    failure for one or more recipients (:blocked) (in

    reply to end of DATA command)

    [ Part 3: "Undelivered Message" ]

edited by tmo_amanda to remove personal info such as email addresses