550 5.7.1 This message is likely unsolicited email
Sample bounce line
550 5.7.1 This message is likely unsolicited email. To reduce the amount of spam sent to Gmail, this message has been blocked. For more information, go to Why has Gmail blocked my messages?
What it means
Gmail's spam filtering judged the message to be likely unsolicited email and blocked it to reduce spam sent to Gmail.
Why it happens
- Message content contains words that look like spam (Google: an email might be blocked if it contains words that look like spam).
- The sender has a history of sending spam.
- Message flagged as spam or sent to too many recipients at once (Fix bounced or rejected emails).
How to fix it
- Remove suspicious links and requests for personal information from the message.
- For large distributions, use Google Groups instead of sending to many recipients at once.
- Review Gmail's Email sender guidelines and make sure SPF, DKIM and (for bulk senders) DMARC are set up.
- Monitor spam rate and reputation in Postmaster Tools (Google advises keeping the spam rate below 0.10% and never reaching 0.30%).
- If you forward mail, follow Google's best practices for forwarding email to Gmail.
DNS record examples (replace example.com and the values with your own):
example.com. IN TXT "v=spf1 include:_spf.your-mail-provider.example ~all" ; one SPF record per domain; use your provider's real include value
_dmarc.example.com. IN TXT "v=DMARC1; p=none; rua=mailto:[email protected]" ; start at p=none, tighten only after reports look clean
Check your domain now
Many of these errors come from missing or broken SPF, DKIM, DMARC or reverse DNS records. Enter your domain to run the free check.
Related errors
- 550 5.7.26 This email has been blocked because the sender is unauthenticated
- 421 4.7.28 Gmail has detected an unusual rate of email originating from your IP address [ip-address]