Emails sent by SES to Germany's largest ISP always bounce

7

Hello,

since 3 days we are unable to send emails to our customers with @t-online.de addresses (Germanys largest isp). All emails bounce with either

"smtp; 550 4.4.7 Message expired: unable to deliver in 840 minutes.<451 4.0.0 Unknown>"

or

"smtp; 554 4.4.7 Message expired: unable to deliver in 840 minutes.<421 IP=54.240.3.22 - No more parallel connections from your address allowed>"

The second message varies with the ip address and is only returned sometimes, about 95% of the bounces contain the first message.

I already contacted the ISP who basically told us the emails server opens too many parallel connections (they didn't responst to the first bounce message)

Martin
asked a year ago1471 views
8 Answers
3
Accepted Answer

Hi All, I received an update from internal SES team that the issue has now resolved. They posted a message on PHD (Personal Health Dashboard) and I also attach the same message below for your reference:

Between October 15 6:20 AM PDT and November 2 9:10 AM PDT, emails that were sent to @t-online.de addresses could have experienced throttling which delayed delivery or timeouts which resulted in emails being returned as bounces. Bounced emails during this period were not delivered and would need to be re-sent. The issue has been resolved and the service is operating normally.

profile pictureAWS
SUPPORT ENGINEER
Oscar_T
answered a year ago
profile picture
EXPERT
reviewed 10 months ago
  • Yes it seems to work again, we had no more bounces since yesterday

2

We had this issue multiple times with t-online.de, magenta.de and telekom.de (they are all the same) blocking all AWS SES mails. normally it gets resoved between the companies after a day but not this time.

answered a year ago
2

We are also affected by this.

Contacted the company and the postmaster gave us basically the same answer as Martin got and added that we should adjust peer concurrency or destination concurrency. Is this something we as SES users can do?

In the guide I found something that sounds related. Is this the way to go?

cdmsn
answered a year ago
2

We have the same problem: emails sent via SES to @t-online.de addresses bounce with the mentioned error since 2022-10-15. The t-online.de postmaster support has told us to reach out to SES support for help.

Update: As mentioned by @Oscar_T, the issue is solved since 2022-11-03.

profile picture
answered a year ago
1

We are also effected by this!

answered a year ago
0

+++ Oct. 28th update +++

If the delivery of e-mails often results in a temporary error (421 IP=*** - No more parallel connections from your address allowed )

this means that the delivering system has tried to establish more simultaneous connections to our servers than allowed, to establish more simultaneous connections to our servers than technically are technically possible.

This anwser comes direct from T Online

How can we prevent this now? We have no parallel connection we only send from our verified domains.

+++

I have still the same Problem. I have the problem with t-online.de, but also web.de, hotmail.com , gmx.net, gmx.de, with these providers we always have problem. But massively since about 15.10.2022. How can we fix the problem quickly, because transactional mail from my store are also affected. So not only marketing emails.

answered a year ago
0

Our customers with t-online.de mail addresses complain massively to us. The advice to refer them to Telekom is kindly meant, but does not help. We feel left alone with the problem and get no help from either AWS or Telekom. Please find a solution as soon as possible. Julian

julian
answered a year ago
-2

Hi Martin, Welcome to AWS re:Post!

=== Oct. 26th update 2 ===

SES team posted a message on Personal Health Dashboard: We are currently experiencing elevated rate of email throttles to Deutsche Telekom email recipients. This is caused by a change in Deutsche Telekom email receiving behaviour. Some customers experiencing throttles may experience a bounced email after the email sending retry period expires. The throttles are impacting a subset of the SES shared and dedicated IP address space across all SES regions. We are actively engaged with Deutsche Telekom to seek resolution of the throttling behaviour. To help expedite this, our recommendation is for impacted senders to have their recipients contact Deutsche Telekom for resolution.

=== Oct. 26th update ===

Based on feedback from multiple customers, this issue also happens to shared IP pools. So the below workaround does not work at the moment. As far as I know the internal team is working on resolving this issue.

=== Previous message ===

If you are sending emails using a Dedicated IP pool, there's a workaround which you may send emails using a Shared IP pool for now. You can create a configuration set and specifying ses-shared-pool for Sending IP pool, and using that configuration set to send emails to t-online.de addresses.

profile pictureAWS
SUPPORT ENGINEER
Oscar_T
answered a year ago
  • We are using a shared pool and having the same issue

  • I'm sorry to hear that. Currently the internal team is aware of this and they are investigating the issue.

  • We are also using the shared pool.

  • we have the same issue for domain-verified identities as well as email-verified identities and tried the dedicated ip pool. the shared and the default. Its not a new issue, it came up on 09-22-2022 for the first time.

  • we also do have the same problem, no matter which pools we use...

You are not logged in. Log in to post an answer.

A good answer clearly answers the question and provides constructive feedback and encourages professional growth in the question asker.

Guidelines for Answering Questions