554: A header field appears more than once
GMX refused the message because a header that RFC 5322 allows only once, such as From, Date, Subject or Message-Id, appears more than once.
- GMX, WEB.DE
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 554
- Provider
- GMX, WEB.DE and mail.com
- 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 Transaction failed
What it means
RFC 5322 section 3.6 allows some header fields only once per message. GMX enforces that, and each of these cases names the field it found twice: Bcc (r0702), Cc (r0703), Date (r0707), From (r0713), In-Reply-To (r0714), Message-Id (r0722), References (r0724), Reply-To (r0725), Sender (r0732), Subject (r0734) or To (r0736). The message is refused with 554. Duplicates usually come from software that adds a header without checking whether one is already there, often a gateway, a plugin or a script that builds messages by hand.
Common causes
- An application or script adds a header that the mail library already set.
- A gateway or signature tool inserts a second Date, Message-Id or Reply-To.
- A template contains a header that the sending software also writes.
How to fix it
- 01Read the GMX case number in the error to see which field is duplicated.
- 02Look at the raw headers of a sent message and find the second copy.
- 03Remove the extra header in the software that adds it, then send again.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
Related codes
- 554Required Date or From header is missing.GMX refused the message because it has no Date header or no From header, both of which RFC 5322 requires in every message.
- 554A header field has invalid syntax.GMX refused the message because a header, such as Date, From, Sender, Subject or To, is not written the way RFC 5322 and RFC 2047 require.
- 554Headers break RFC 5322.IONOS refused the message because its headers do not follow RFC 5321 and RFC 5322: a missing or doubled Date, or a From, Sender, To, Cc or Subject header that is repeated or malformed.
- 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.
- 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 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.
Further reading
All 57 GMX, WEB.DE codesEvery code in the wikiPaste your own bounce