IONOS (1&1) · permanent error
554: IP address on a DNS blocklist
IONOS refused your mail because your sending IP has an entry on a DNS blocklist (DNSBL). IONOS will check an entry you believe is wrong.
- 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 IP address is blacklisted
What it means
IONOS consults DNS-based blocklists when a server connects. This 554 means your sending IP is listed on one of them, so mail from it is refused. The help page does not name the list. Its remedy is to contact IONOS to have an incorrect entry checked. Before you do, look the IP up on the common public blocklists: if it is listed somewhere, the removal has to happen at that list.
Common causes
- Spam or malware traffic from the IP was reported to a blocklist.
- The IP belongs to a range a blocklist lists, such as dynamic addresses.
- A previous user of the IP left it listed.
How to fix it
- 01Check the IP on the common public blocklists.
- 02Fix whatever caused a listing and request removal from that list.
- 03If you believe the entry is wrong, contact IONOS to have it checked, quoting the full error.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 554IP address on a Spamhaus blocklist.GMX refused the connection because your sending IP is listed on a Spamhaus blocklist. GMX makes no exceptions; the listing has to be removed at Spamhaus.
- 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 17 IONOS codesEvery code in the wikiPaste your own bounce