smtp;450 User is receiving mail too quickly
The receiver deferred this message and will retry it automatically. A failure that sticks around usually traces back to rate limits, reputation, or a policy on the receiving side.
Provider documentation
Email provider · 4.x.x transient failure
Yahoo Inc SMTP 450 Errors: Every Bounce Response Explained
Every SMTP 450 response on record from Yahoo Inc (yahoo.com, aol.com, verizon.net), with the verbatim text, the enhanced status code, a severity rating and a plain-English fix.
The requested action did not happen because the mailbox was briefly unavailable, for example locked, busy, or lightly rate limited. The sending server keeps the message queued and retries it.
- Provider
- Yahoo Inc
- Code
- 450 (4xx)
- Responses
- 1
- Highest severity
- Medium
Yahoo Inc SMTP 450 responses
Postmaster & documentation
Yahoo Inc SMTP 450 questions
›What does an SMTP 450 error from Yahoo Inc mean?
The requested action did not happen because the mailbox was briefly unavailable, for example locked, busy, or lightly rate limited. The sending server keeps the message queued and retries it. At Yahoo Inc, it is a temporary deferral that is retried automatically, and the specific reason is in the enhanced status code and message text of each response below.
›How do I stop Yahoo Inc from returning SMTP 450?
Match your bounce text to one of the responses below and follow its guidance. Recipient-side wording means fix the address. Authentication or reputation wording (SPF, DKIM, DMARC, blocklist) means fix your sending setup, and check Yahoo Inc's postmaster documentation.