Gmail 550 5.7.40
Blocked: no DMARC policy
Gmail 550 5.7.40 means: blocked: no DMARC policy. It is a permanent failure, so do not retry it unchanged. Publish a DMARC record with a policy on the From domain; Gmail requires it for bulk senders.
Gmail’s exact wording
Quoted from Google Workspace Admin Help: Gmail SMTP errors and codes, checked 2026-11-05. Placeholders are Gmail’s own.
Reply text
Your message was blocked because the sending domain doesn't have a DMARC record or the DMARC record doesn't specify a DMARC policy. Gmail requires all bulk email senders to add a DMARC record to their sending domain. See Set up DMARC. To learn more about Gmail requirements for bulk email senders, visit Email sender guidelines.
| Who sends it | Gmail and Google Workspace |
|---|---|
| Basic code | 550: Requested action not taken: mailbox unavailable (e.g., mailbox not found, no access, or command rejected for policy reasons) (RFC) |
| Enhanced code | 5.7.40: Gmail-specific, not in the IANA registry. Its subject digit puts it under 5.7.0 other or undefined security status. |
| Permanent or temporary | Permanent (5xx) |
| Verifying the list prevents it | No |
In practice
Gmail lists 5.7.40 under two basic codes with different meanings. 550 5.7.40 is the permanent block for bulk mail from a domain with no DMARC policy. 504 5.7.40 is an authentication error for an unrecognised AUTH type, including the retired XOAUTH mechanism. For the DMARC version, publish a DMARC record on the From domain. The record can start at p=none.
What the sender should do
Publish a DMARC record with a policy on the From domain; Gmail requires it for bulk senders.
Would verifying the list have prevented Gmail 550 5.7.40?
No
This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Common questions
- What does Gmail 550 5.7.40 mean?
- Gmail 550 5.7.40 means: blocked: no DMARC policy. It is a permanent failure, so do not retry it unchanged. Publish a DMARC record with a policy on the From domain; Gmail requires it for bulk senders.
- Should I retry after Gmail 550 5.7.40?
- No. It is a permanent (5xx) failure, so the same message to the same address will fail again. Fix the cause first. Publish a DMARC record with a policy on the From domain; Gmail requires it for bulk senders.
- Would verifying my list have prevented Gmail 550 5.7.40?
- No. This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Sources
- Google Workspace Admin Help: Gmail SMTP errors and codes (checked 2026-11-05)
- RFC 5321: Simple Mail Transfer Protocol, section 4.2.3 (reply codes) (checked 2026-11-05)
Registry and provider wording is quoted exactly; guidance is written by the SimpleVerifier Team.
SimpleVerifier Team · Last checked against the sources 2026-11-05