554: blocked by Barracuda Reputation
Barracuda’s own IP reputation list scores your sending server as a spam source, so every Barracuda gateway checking it refuses your mail.
- Barracuda
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 554
- 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 Service unavailable; client host [IP or hostname] blocked using Barracuda Reputation
What it means
Barracuda gateways check connecting IPs against the Barracuda Reputation System, which also runs as the public Barracuda Reputation Block List (BRBL). This reply means the IP that delivered your message is listed there, and the gateway in front of the recipient refused it permanently. Because many companies run Barracuda, the listing can affect mail to any of them, not just this one. Barracuda says the list is generated by automated systems and accepts removal requests at barracudacentral.org, which it typically processes within 12 hours when a valid explanation is given.
Common causes
- Your IP sent mail that Barracuda’s systems scored as spam.
- A compromised account or device used your IP to send spam.
- The IP was listed before you started using it, or is shared with other senders.
How to fix it
- 01Look up your IP on barracudacentral.org to confirm the listing.
- 02Fix what caused it: secure accounts, stop sending to unengaged or unconsented lists, check for malware.
- 03Submit one removal request at barracudacentral.org with your IP, email address, phone number and a short explanation; Barracuda ignores repeated requests.
- 04Wait for the review, usually within 12 hours, before resending.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- SMTP Error Codes, Barracuda Email Security Gateway documentationdocumentation.campus.barracuda.com
- Barracuda Central Reputation System, removal requestbarracudacentral.org
Related codes
- 554Transaction failed.The server permanently refused the transaction, often after receiving the message data or straight away when the connection opened.
- 554Sending IP or domain on a real-time blocklist.The recipient’s Barracuda gateway refused the connection because your sending IP or domain may be on a real-time blocklist (RBL) it checks.
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 11 Barracuda codesEvery code in the wikiPaste your own bounce