554: reverse DNS does not meet IONOS policy
IONOS refused your mail because the PTR record of your IP does not meet its policy, typically a generic or dynamic-looking provider name.
- IONOS
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 554
- Provider
- IONOS (1&1)
- 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 Bad DNS PTR resource record
What it means
Your sending IP has reverse DNS, but IONOS does not accept the name it returns. Its help page points to the usual reasons: a dynamically assigned IP address, or a PTR record that is still the generic default entry of the provider rather than a name for your own mail server. IONOS asks you to switch to a fixed IP, check whether the PTR record is the provider default, and give the server its own fully qualified domain name. After the change, mail from the IP is accepted again.
Common causes
- The IP is dynamically assigned, such as a home or office connection.
- The PTR record is the provider default built from the IP address.
- The PTR name does not belong to your own domain.
How to fix it
- 01Send from a fixed IP address assigned to your mail server.
- 02Have the PTR record changed to a fully qualified name in your domain.
- 03Make that name resolve back to the same IP.
- 04If you cannot control the PTR, send through a relay with proper reverse DNS.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 554No reverse DNS for your IP.IONOS refused your mail because the IP address of your mail server has no domain name assigned to it in DNS (no PTR record).
- 554Reverse DNS does not meet GMX requirements.GMX refused the connection because the reverse DNS (PTR) record of your IP looks generic or dynamic. GMX expects a fixed IP with its own mail host name.
- 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.
- 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.
Further reading
All 17 IONOS codesEvery code in the wikiPaste your own bounce