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Google SMTP 450 Errors: Every Bounce Response Explained

Every SMTP 450 response on record from Google (gmail.com, googlemail.com), 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
Google
Code
450 (4xx)
Responses
1
Highest severity
Medium

Google SMTP 450 responses

Status 4.2.1Medium severity#
smtp;450 4.2.1 The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, please visit https://support.google.com/mail/?p=ReceivingRate - gsmtp

You are sending faster than this receiver currently accepts from you. Slow down and the automatic retry will deliver the queued mail.

Provider documentation

Postmaster & documentation

Google SMTP 450 questions

›What does an SMTP 450 error from Google 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 Google, 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 Google 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 Google's postmaster documentation.

All SMTP 450 responsesAll Google error codes

Other error codes seen from Google