Gmail 452 4.5.3
Too many recipients
Gmail 452 4.5.3 means: too many recipients. It is a temporary failure, so your server retries it. Send fewer recipients per message, or the rest of the recipients in a separate transaction.
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
Domain policy size per transaction exceeded, please try this recipient in a separate transaction. For more information, go to Message bounced due to a policy rule.
Reply text
Your message has too many recipients. For more information regarding Google's sending limits, go to Limits for sending & getting email.
| Who sends it | Gmail and Google Workspace |
|---|---|
| Basic code | 452: Requested action not taken: insufficient system storage (RFC) |
| Enhanced code | 4.5.3: Too many recipients |
| Permanent or temporary | Temporary (4xx) |
| Verifying the list prevents it | No |
In practice
Gmail lists two versions: too many recipients for its sending limits, and a domain policy that limits recipients per transaction, where Google asks you to try that recipient in a separate transaction. Well-behaved mail servers split recipients across transactions automatically. Scripts that put hundreds of addresses in one message, or in the To and Cc headers, are the usual cause. The recipient addresses are not the problem.
What the sender should do
Send fewer recipients per message, or the rest of the recipients in a separate transaction.
Would verifying the list have prevented Gmail 452 4.5.3?
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 452 4.5.3 mean?
- Gmail 452 4.5.3 means: too many recipients. It is a temporary failure, so your server retries it. Send fewer recipients per message, or the rest of the recipients in a separate transaction.
- Should I retry after Gmail 452 4.5.3?
- Your sending server retries it automatically, because it is a temporary (4xx) failure. Investigate only if it keeps coming back over several hours.
- Would verifying my list have prevented Gmail 452 4.5.3?
- 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.
The same code elsewhere
Sources
- Google Workspace Admin Help: Gmail SMTP errors and codes (checked 2026-11-05)
- IANA: SMTP Enhanced Status Codes registry (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