Gmail and Google Workspace · permanent error
550 5.7.30: DKIM did not pass, blocked
Gmail rejected the message because it failed DKIM, which Gmail requires of bulk senders along with SPF.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 550 5.7.30
- 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 5.7.30 This message was blocked because it didn't pass DKIM authentication.
What it means
This is the permanent form of 421 4.7.30. Anyone sending more than 5,000 messages a day to Gmail accounts must pass DKIM as well as SPF, and this message had no valid DKIM signature: none at all, one that did not verify, or one whose public key Gmail could not find in DNS. Google lists the code in its sender guidelines FAQ. Turn on signing, publish the selector record, and make sure nothing alters the message after it is signed.
Common causes
- DKIM signing is not turned on at the sending service.
- The selector record is missing from DNS or does not match the signing key.
- A gateway or list changed the message after it was signed.
How to fix it
- 01Turn on DKIM signing at every service that sends for your domain.
- 02Publish each selector record and check it with a DKIM lookup.
- 03Stop changes to messages after signing, or have the last hop sign.
- 04Resend once a test message to Gmail shows dkim=pass.
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
- Email sender guidelines (Gmail Help)support.google.com
Related codes
- 421 4.7.30DKIM did not pass, rate limited.Gmail is rate limiting your mail because it failed DKIM, which Google requires of bulk senders along with SPF.
- 550 5.7.27SPF did not pass, blocked.Gmail rejected the message because it failed SPF, which Gmail requires of bulk senders along with DKIM.
- 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.
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce