550 5.7.30 Gmail bounce: DKIM not passed
What 550 5.7.30 means
Gmail blocked the message because DKIM did not pass, which Gmail requires for bulk senders.
Message text
This message was blocked because it didn't pass DKIM authentication.
Common causes of 550 5.7.30
- Message has no DKIM signature
- DKIM public key in DNS is missing or does not match the signing key
- Message body changed after signing, for example by a forwarding footer
How to fix 550 5.7.30
- Run DKIM checker with the selector your sending service uses.
- Make sure the DKIM signing domain aligns with the From domain.
- Inspect the DKIM-Signature header with email header analyzer.
Check your domain
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Have the full bounce message? Paste it into the bounce code lookup and it will match the code and the provider for you. Open the bounce code lookup.
How to read 550 5.7.30
The first part, 550, is the SMTP reply code. Requested action not taken, mailbox unavailable: the mailbox does not exist, is not allowed, or the message was refused for policy reasons. Replies that start with 4 are temporary and replies that start with 5 are permanent (RFC 5321 §4.2.1).
The second part, 5.7.30, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 7 is security or policy: authentication, authorization or policy refused the message. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.
Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.
Official source: knowledge.workspace.google.com. Last verified 2026-10-20.
Related guides
- How DKIM works and how to publish a DKIM record
- DKIM key length: 1024 vs 2048 bits (and Ed25519)
- How to set up a DMARC record, from p=none to p=reject
Related codes
- 5.7.0 SMTP: security status
- 5.7.1 SMTP: delivery not authorized
- 5.7.23 SMTP: SPF validation failed
- 5.7.25 SMTP: reverse DNS failed
- 5.7.26 SMTP: authentication failed
- 5.7.27 SMTP: sender has null MX
FAQ
What does 550 5.7.30 mean?
Gmail blocked the message because DKIM did not pass, which Gmail requires for bulk senders. This is a permanent failure.
How do I fix 550 5.7.30?
Run DKIM checker with the selector your sending service uses. Make sure the DKIM signing domain aligns with the From domain. Inspect the DKIM-Signature header with email header analyzer.
Is 550 5.7.30 permanent, and should I retry?
550 5.7.30 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.