Status 4.3.2#
smtp;451 4.3.2 Temporary server error. Please try again later ATTR17 [outlook.com]
You are sending faster than this receiver currently accepts from you. Slow down and the automatic retry will deliver the queued mail.
Email provider · 4.x.x transient failure
Outlook SMTP 451 Errors: Every Bounce Response Explained
Every SMTP 451 response on record from Outlook (hotmail.com, outlook.com, msn.com, live.com), with the verbatim text, the enhanced status code, a severity rating and a plain-English fix.
The receiver aborted the action because of a local error on its side, such as greylisting, a reputation or content check still running, or a short policy hold. Retries normally succeed once the hold clears.
- Provider
- Outlook
- Code
- 451 (4xx)
- Responses
- 5
- Highest severity
- High
Outlook SMTP 451 responses
smtp;451 4.4.0 Message failed to be replicated: No healthy secondary server available to accept replica at this time. [outlook.com]
The receiver deferred the message and points at a network or routing problem (enhanced status 4.4.0). Use the wording above to pin down the exact fix.
smtp;451 4.7.0 Temporary server error. Please try again later. PRX6 NextHop: outlook.com [outlook.com]
You are sending faster than this receiver currently accepts from you. Slow down and the automatic retry will deliver the queued mail.
451 4.7.650 The mail server [x.xx.xx.xx] has been temporarily rate limited due to IP reputation. For e-mail delivery information, see https://postmaster.live.com (S843)[#.prod.protection.outlook.com]
You are sending faster than this receiver currently accepts from you. Slow down and the automatic retry will deliver the queued mail.
451 4.7.651 The mail server [x.xx.xx.xx] has been temporarily rate limited due to IP reputation. For e-mail delivery information, see https://postmaster.live.com (S3114) [#.prod.outlook.com #]
You are sending faster than this receiver currently accepts from you. Slow down and the automatic retry will deliver the queued mail.
Outlook SMTP 451 questions
›What does an SMTP 451 error from Outlook mean?
The receiver aborted the action because of a local error on its side, such as greylisting, a reputation or content check still running, or a short policy hold. Retries normally succeed once the hold clears. At Outlook, 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 Outlook from returning SMTP 451?
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 Outlook's postmaster documentation.