554: IP address blocked
Telekom is not accepting mail from your IP address at all, usually after unusual mail volume from it. The reply names the contact to ask for review.
- Telekom
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 554
- Provider
- Telekom (t-online.de)
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
554 A problem occurred. (Ask your postmaster for help or to contact tosa@rx.t-online.de to clarify.)
What it means
When a t-online.de server answers the connection with 554 and the words "A problem occurred", then hangs up, the IP shown is blocked from delivering mail. Telekom says such blocks follow unusual mail volume from the address. Mail to its spam traps, customer complaints and SMTP error rates above 3% at peak or 1.5% on average can lead to the same measure. A block can also meet an IP you never sent from before, because its cause may lie far back. Some older mail servers treat the closed connection as temporary and keep retrying without showing the error.
Common causes
- Unusual volume or patterns of mail from the IP.
- Mail to Telekom spam traps, or complaints from t-online.de customers.
- A high rate of SMTP errors, such as sending to unknown addresses.
- The IP was used for abuse before you received it.
How to fix it
- 01Find out what triggered the block in your logs: volume, bounces, complaints or abuse.
- 02Fix the cause, including bounce handling and list hygiene.
- 03Write to the contact named in the error (tosa@rx.t-online.de), or use the Telekom postmaster online form, giving the blocked IP.
- 04If your system is suspended, write to postmaster@rx.t-online.de rather than postmaster@t-online.de.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- t-online.de Postmaster (Deutsche Telekom)postmaster.t-online.de
Related codes
- 550 5.7.0Message classified as spam or virus.The Telekom spam filter classified your message as spam or as carrying a virus and rejected it after the DATA phase. False positives can be reported.
- 554IP address on the GMX blocklist.Your sending IP is on a blocklist that GMX manages itself, so its servers refuse the connection. GMX keeps a strict no tolerance policy toward spam.
- 554Transaction failed.The server permanently refused the transaction, often after receiving the message data or straight away when the connection opened.
554 at other providers
- 554Permanent rejection (554).Yahoo or AOL rejected the message for good with a 554. Yahoo uses this code for several problems, from failed authentication to unacceptable content, so the wording of the reply tells you which.
- 554Failed authentication.Yahoo or AOL refused the message because it failed the checks that confirm the sending domain, such as DKIM against the domain's policy. Yahoo lists this among its permanent 553 and 554 errors.
- 554Recipient does not exist.The Yahoo or AOL account you wrote to does not exist. The failure is permanent: check the address with the recipient, and remove it from any list.
- 554No reverse DNS (PTR) record.Xfinity refused the connection because your sending IP has no PTR record. Every server sending to Xfinity needs valid reverse DNS, so the owner of the IP must add one.
- 554Rejected for breaking GMX guidelines.GMX refused the message permanently because the connection broke its guidelines. GMX points to its requirements page and asks for the full error message if the problem continues.
Further reading
All 3 Telekom codesEvery code in the wikiPaste your own bounce