550 5.7.1: blocked for low domain reputation
Gmail permanently rejected the message because the domain it comes from has a very low reputation with Gmail.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 550 5.7.1
- Provider
- Gmail and Google Workspace
- 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 5.7.1 This message is likely suspicious due to the very low reputation of the sending domain.
What it means
This is the permanent form of the domain reputation block. Gmail's record of mail from your domain, built mostly from how recipients have reacted to it, is poor enough that it now rejects messages from it. Domain reputation follows the domain across IPs and providers, so changing infrastructure does not fix it. Recovery means sending less, and only to people who want your mail, while Postmaster Tools shows reputation and spam rate improving. Google's sender guidelines FAQ asks senders to keep their spam rate below 0.1% and never let it reach 0.3%.
Common causes
- High spam complaint rates on mail from the domain.
- Mail sent to lists with many invalid or uninterested recipients.
- A new domain that sent large volumes before it had any history.
- Others sending as the domain because it lacks strict authentication.
How to fix it
- 01Check domain reputation and spam rate in Google Postmaster Tools.
- 02Cut volume sharply and send only to your most engaged recipients.
- 03Make sure SPF, DKIM and DMARC pass and align for every stream on the domain.
- 04Remove recipients who never engage, and make unsubscribing easy.
- 05Raise volume again only as the reputation recovers.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
- Email sender guidelines FAQ (Gmail Help)support.google.com
Related codes
- 421 4.7.0Low domain reputation.Gmail has turned away this message because the domain it comes from has a very low reputation with Gmail.
- 550 5.7.1Blocked as likely spam.Gmail's filters judged this message likely to be spam and rejected it outright, instead of delivering it to the spam folder.
- 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.
- 5.7.1Delivery not authorised.The receiving server refuses the message because this sender is not allowed to send to this recipient, as a result of filtering by host or by recipient.
5.7.1 at other providers
- 550 5.7.1Not authorized to send to this recipient.You do not have permission to send to this recipient, typically a group restricted to certain senders or a recipient protected by a mail flow rule.
- 550 5.7.1Public folder does not accept external mail.An external sender wrote to a mail-enabled public folder in Microsoft 365, which by default accepts mail only from authenticated senders.
- 550 5.7.1Sending IP blocked by Proofpoint Dynamic Reputation.Proofpoint’s IP reputation system has your sending IP on its block list because it has seen spam or viruses from it, so Proofpoint customers refuse your mail.
- 550 5.7.1SPF check failed.The recipient’s Cisco Secure Email gateway checked SPF, found your server not authorised for the sender domain, and its policy rejects that result.
- 550 5.7.1Rejected under your domain’s DMARC policy.Your message failed DMARC, your domain’s DMARC record asks receivers to reject such mail, and the recipient’s Cisco gateway did so.
- 550 5.7.1DMARC verification failed permanently.The Cisco gateway hit a permanent failure while verifying DMARC for your message, and the recipient’s policy rejects such mail. Cisco does not say what produces that failure.
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce