Hi there - we experience huge problems with bounces to all address (which is Germany’s biggest online provider, hence a big problem for as as Germany is our key market). Essentially all e-mails to bounce for several months already, and we now have several thousand suppressed profiles because of that.

I contacted Klaviyo several times and they always say they will look into it (and trying one more time now), however the problem persists.

Does anyone have any advice on how to best address this? Is this something Klaviyo needs to fix (i.e. is Klaviyo getting blocked), or is our domain the problem? Note we just started to set up our own domain in Klaviyo (have added DNS accordingly), but no results yet.

Also does anyone know how I can un-suppress the profiles in bulk?

Thanks for the help, any advice highly appreciated!


Best answer by cassy.lee 7 May 2021, 16:31

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32 replies


And another completely-standard answer not answering my questions at all...


 (Klaviyo D&C) 

Aug 5, 2021, 3:37 PM EDT 

Hi there,

Because we use a range of rotating IPs, we are unable to share, as it would not be accurate or feasible to provide the range to our users.

T-online has recently instituted some unique requirements that are needed of a sender to ensure inbox placement. You can read about these requirements in our guide on the topic here. These have impacted the entire email sending industry and are not specific to Klaviyo.

The bounce reason will differ in the IP address that was used for that specific send, but the bounces are:
554 IP= - A problem occurred. (Ask your postmaster for help or to contact to clarify.)

--with differing IPs, as mentioned.

If your account is unable to meet these requirements at this time, we would recommend creating a segment using a condition like the one below and excluding the said segments from your campaign sends. This will prevent profiles having a series of bounces on their timeline which in turn will make sure that they are not suppressed for email sending in the future.


Do let us know if we can help with anything else in the meantime!



I got another answer from the t-online postmaster. They told me that Klaviyo has to contact them.


New answer from the t-online postmaster:

The problem is, that Klaviyo uses a lot of IPs from different network areas. We already released some IPs from Klaviyo but that’s why we need to know about which IPs exactly we are talking.


Please, dear Klaviyo, contact the t-online postmaster and tell them from which IPs you are sending our mails.

Hello to all,

nice that the discussion is so intense again.

The more I read, the more annoyed I became. Because the problem has now become a medium disaster. Problems don't get smaller if you ignore them!

I do not understand that this post were marked as solved. The opposite is the case!

I was asked by Klaviyo to set up a dedicated sending domain, which I did 2 months ago. 
Statement was that Klaviyo will approach T-Online in my name afterwards.

Until today I did not get an answer despite several contacts with the support.
The bouncerate of the mails to t-online has therefore not improved.


The solution with a dedicated sending IP is not feasible for the majority of Klaviyo customers. 
What does the Klaviyo team plan to do to solve the problem?




Hi @Erik,

We hear you and are taking action.  We will attempt again to work with T-online to get the Shared IPs unblocked.  We have been turned away in the past because they are shared IPs and not Dedicated with custom PTR Records.  However, the responses we have seen recently to customers shows that they may have lightened up on this stance.  We will update you as soon as we learn more.  Thank you very much for your continued understanding in this matter.

Thanks again, 


Same issue here… I have just send the first newsletter and all addresses got bounced.

It would be good, if Klaviyo could warn users about such addresses, as there is little we can do to prevent these bounces without knowing the issue beforehand.

By the way: addresses are very popular in Germany, unfortunately.

Hey everyone! 


My name is Francis, I am a Deliverability and Compliance technical specialist here at Klaviyo. I wanted to follow-up on this thread and provide some more information. 

Klaviyo is actively looking into joining CSA. The CSA application is extensive, and before we can meet all the standards and requirements, they have we need to do some technical changes. We are actively working on these technical changes, as well as working with CSA.

T-Online is currently not listed as a member of CSA, so yes, the CSA Certification has great benefit. We currently have no evidence, that it will assist with making inbox placement at T-Online easier. Here is a list of all ESP’s and MBP’s that currently take advantage of the CSA Certificate.

We understand, how difficult this situation is, and we are all feeling it in the industry. Klaviyo is actively working on ways to make this better and smoother. Deliverability has always been a top priority and will continue to be.