550: permanent reject under an exceptional blocklist
GMX permanently refused mail from your system because it is on one of the blocklists GMX uses in exceptional situations. The message comes back and is not retried.
- GMX, WEB.DE
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 550
- 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
550 Reject due to policy violations
What it means
Cases r0005 and r0006 are the permanent form of the GMX exceptional blocklists. The reply starts with 550, so your server stops trying and returns the message to the sender. GMX uses these lists to protect its infrastructure from connections and spam it judges to be abuse, and the case page names no single trigger. What it asks is the same as for the temporary forms: stop the misuse of your system, then contact the postmaster team through the form on the case page so it can review the block.
Common causes
- Your system sent spam or unwanted connections to GMX, WEB.DE or mail.com addresses.
- An account or service on your system was compromised and used to send abuse.
How to fix it
- 01Stop all sending to GMX, WEB.DE and mail.com addresses until you know what triggered the block.
- 02Find and remove the source of unwanted mail: compromised accounts, open relays, unauthorised scripts.
- 03Check that your IP and domain are not listed on public blocklists as well.
- 04Once the cause is fixed, use the contact form on the case page (or postmaster.gmx.net/en/contact) and include the full last line of the error, your IP addresses and your domain.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- GMX Postmaster case r0005: 550 Reject due to policy violationspostmaster.gmx.net
- GMX Postmaster case r0006: 550 Reject due to policy violationspostmaster.gmx.net
Related codes
- 421Temporary reject under an exceptional blocklist.GMX refused the connection from your server for now under one of the blocklists it applies in exceptional situations. Your server will retry; GMX asks you to stop the misuse first, then contact it.
- 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.
- 550Mailbox unavailable.The receiving server permanently refused the message for this recipient: the mailbox does not exist, cannot be reached, or the server rejected the message by policy.
550 at other providers
- 550 [SC-001]Outlook.com policy block for content or reputation.Outlook.com rejected the mail for policy reasons tied to spam-like content or to the reputation of the sending IP or domain.
- 550 [SC-002]Outlook.com block for namespace mining.Outlook.com blocked the sending IP because it behaved like a namespace miner, checking whether addresses exist without sending mail.
- 550 [SC-003]Outlook.com block for an open proxy or relay.Outlook.com rejected the mail because the sending IP appears to be an open proxy or open relay.
- 550 [SC-004]Outlook.com block after complaints.Outlook.com placed a block on the sending IP because it received complaints about mail coming from it.
- 550 [DY-001]Outlook.com refuses dynamic IP addresses.Outlook.com rejected the mail because the sending IP is dynamic address space, which it generally does not accept mail from.
- 550 [DY-002]Outlook.com block for a likely compromised sender.Outlook.com rejected the mail because the sending server or computer appears to be compromised or infected.
Further reading
All 57 GMX, WEB.DE codesEvery code in the wikiPaste your own bounce