Gmail 550 5.5.3
Too many recipients for this sender
Gmail 550 5.5.3 means: too many recipients for this sender. It is a permanent failure, so do not retry it unchanged. Split the send into smaller batches within Google's limits.
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
Too many recipients for this sender. For more information, go to About SMTP error messages and review RFC 5321 specifications.
| 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 | 5.5.3: Too many recipients |
| Permanent or temporary | Permanent (5xx) |
| Verifying the list prevents it | No |
In practice
Google limits how many recipients one account can address per message and per day. Splitting into smaller batches only helps within the daily limit, so for newsletters and campaigns use a sending service rather than a Gmail or Workspace mailbox. The recipients themselves are fine.
What the sender should do
Split the send into smaller batches within Google's limits.
Would verifying the list have prevented Gmail 550 5.5.3?
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 550 5.5.3 mean?
- Gmail 550 5.5.3 means: too many recipients for this sender. It is a permanent failure, so do not retry it unchanged. Split the send into smaller batches within Google's limits.
- Should I retry after Gmail 550 5.5.3?
- No. It is a permanent (5xx) failure, so the same message to the same address will fail again. Fix the cause first. Split the send into smaller batches within Google's limits.
- Would verifying my list have prevented Gmail 550 5.5.3?
- 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.
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