Barracuda 550 permanent failure for one or more recipients
550 permanent failure for one or more recipientsBarracuda gateway message blockPermanent: retrying will not helpFrom Barracuda
550 permanent failure for one or more recipients (user@example.com:blocked)
What it means
This text comes from a Barracuda Email Security Gateway or the cloud service the recipient uses. It accepted the SMTP conversation, scanned the message, and then refused delivery. The part in brackets lists each affected recipient followed by a short reason after the colon. “blocked” is the most common one and means a filter rule decided to block, rather than quarantine or tag, the message.
Which rule fired is not in the bounce. It can be the spam score crossing the block threshold, a sender or domain on the recipient’s block list, an attachment filter, a content filter, or a failed authentication check. The recipient’s admin can see the exact reason in Barracuda’s message log.
Because the scan happens per recipient policy, some recipients in the same message may receive it while others are blocked, which is why the text says “one or more”.
Likely causes
- A spam score above the recipient’s block level, often from a poor reputation for your links or images.
- Your address or domain is on the recipient organization’s Barracuda block list.
- An attachment type the organization blocks, such as executable files, scripts, or encrypted archives.
- A content filter rule on words in the subject or body.
- SPF hard fail or a DMARC failure on a domain whose policy is reject.
How to fix it
- Note which recipients show :blocked in the bounce and which were delivered.
- Send the bounce to your contact so their IT team can search Barracuda’s message log for the exact rule.
- Resend without attachments and with fewer links to see whether content is the trigger.
- Check that your SPF, DKIM, and DMARC pass, since a hard SPF fail can be blocked outright by Barracuda.
- If you are on their block list by mistake, the admin removes the entry or adds an exemption for your domain.
Checks that apply
- SPF Check Evaluates your SPF record, because Barracuda gateways can block on an SPF hard fail before any other scoring.
- Email Header Analyzer Reads a delivered copy for authentication results and suspicious link domains that might raise the spam score.
- Blacklist Check Rules out a DNSBL listing on your IP, which would feed Barracuda’s score even when the BRBL itself does not block you.
FAQ
- Will Barracuda retry the message?
- No. It is a 550, so the message is returned. Fix the cause and send again.
- What does :blocked mean in the bounce?
- It means a Barracuda policy chose to block the message for that recipient. The specific rule is only visible to the recipient’s admin.