We are trying to send emails to t-online inbox but emails aren't getting delivered after 18th December,2019. Prior to this date, everything was working fine but all of a sudden emails stopped getting delivered. However, emails are getting delivered to other email clients. Below options were tried to send emails : 1. Through Send test option in Marketing Cloud 2. Through Postman

  • I would suggest, first can you try sending the same email [with same HTML body and same SubjectLine] using PutsMail [putsmail.com/tests/new] and confirm, if the email is delivered! ....If NOT then you can debug within Marketing cloud. Jan 9, 2020 at 7:13
  • Hi Vishal.. Thanks for the suggestion. yes, i got the email delivered to t-online through Putsmail. What should be my next step now ? Jan 9, 2020 at 7:37
  • Can you also confirm, this is with respect to ONLY particular subscriber! [as the particular might have UNSUBSCRIBED] .... Also can you confirm if it might have landed to SPAM folder!..... Jan 9, 2020 at 7:45
  • Yes, this is happening with a particular subscriber. In our case, its the email address of t-online email client. I checked the status and it says "Bounced". Jan 9, 2020 at 7:54
  • Thanks for sharing the status..... As a last CREATE a new blank test email and see it if gets delivered..... For how to handle about BOUNCED emails, pls read the answer here ... salesforce.stackexchange.com/questions/165399/… Jan 9, 2020 at 8:03

1 Answer 1


T-Online is notorious for reputation-related delivery problems coming from Salesforce Marketing Cloud domains.

Case in point: In the course of an IP warming, we literally sent 1 (one) email off a new, cold IP to t-online, and got a blocked bounce message back. Which clearly shows, t-online seems to block even if you don't "overpower" / send too much to them. For undisclosed reasons, to my knowledge.

So first thing - make sure you follow the rules. I understand that all other clients have no issue with your emails, but you can never be too safe. If you are sure everything is fine, skip the part between the "=".


  • Ensure that you are not having a messy IP reputation to begin with, e.g. go to https://senderscore.org/.

  • Check that you are not blacklisted or fail at best practices with your emails (tons of factors from DKIM to text/image ratio...). Having an SAP covers the DKIM part, btw., as it authenticates your domain for sending.

You can verify those topics with the following tools:




If you are sure that you have no issues here (for our intents and purposes, you can ignore missing DMARC, which is often highlighted by mail-tester):


Now, verify what the issue is in your case: Query the _Bounce Data View for the BounceReason.


Just for full picture, query these fields:





I suspect you will find indications of block bounce "due to reputation" or similar reasoning.

So our situation likely is: We cleaned in front of our own door, found no issue with reputation, anyway we're blocked. That is the time to raise a support ticket with the deliverability team. Support will likely get in touch with t-online and try and resolve the issue "politically". This is a rather routine thing actually. Normally, you should see the issue resolved in a matter of a day or two.

hope this helps!

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