Email provider
Outlook SMTP Error Codes and Bounce Messages
Outlook covers the consumer hotmail.com, outlook.com, live.com and msn.com addresses that sit under Microsoft. Legitimate mail landing in junk usually needs a sender support request, while an IP-level block has to be appealed by whoever controls the IP.
- Codes on record
- 7
- Responses
- 15
- Domains
- hotmail.com, outlook.com, msn.com, live.com
SMTP 4211 response
A temporary problem. The sending server keeps retrying for a while, and delivery often recovers on its own once the underlying issue clears. See SMTP 421 across every provider
SMTP 4501 response
A temporary problem. The sending server keeps retrying for a while, and delivery often recovers on its own once the underlying issue clears. See SMTP 450 across every provider
SMTP 4515 responses
smtp;451 4.3.2 Temporary server error. Please try again later ATTR17 [outlook.com]
smtp;451 4.4.0 Message failed to be replicated: No healthy secondary server available to accept replica at this time. [outlook.com]
smtp;451 4.7.0 Temporary server error. Please try again later. PRX6 NextHop: outlook.com [outlook.com]
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]
A temporary problem. The sending server keeps retrying for a while, and delivery often recovers on its own once the underlying issue clears. See SMTP 451 across every provider
SMTP 4521 response
A temporary problem. The sending server keeps retrying for a while, and delivery often recovers on its own once the underlying issue clears. See SMTP 452 across every provider
SMTP 5011 response
A hard failure. The receiving server has refused the message for good and will not accept an unchanged retry without a change on the sending side. See SMTP 501 across every provider
SMTP 5504 responses
smtp;550 5.5.0 Requested action not taken: mailbox unavailable. [#.eop-nam12.prod.protection.outlook.com]
smtp;550 5.7.1 Service unavailable, MailFrom domain is listed in Spamhaus. To request removal from this list see https://www.spamhaus.org/query/lookup/ (S8002) [#.eop-nam02.prod.protection.outlook.com]
smtp;550 5.7.1 Unfortunately, messages from [x.xx.xx.xx] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [#.eop-nam02.prod.protection.outlook.com]
smtp;550 5.4.1 All recipient addresses rejected : Access denied [#.eop-nam02.prod.protection.outlook.com]
A hard failure. The receiving server has refused the message for good and will not accept an unchanged retry without a change on the sending side. See SMTP 550 across every provider
SMTP 5542 responses
smtp;554 5.2.122 The recipient has exceeded their limit for the number of messages they can receive per hour. For more information go to http://go.microsoft.com/fwlink/?LinkId=526653. (#) [outlook.com]
smtp;554 5.2.121 The sender has exceeded the limit for the number of messages they can send to this recipient per hour. For more information go to http://go.microsoft.com/fwlink/?LinkId=526653. [#.prod.outlook.com #]
A hard failure. The receiving server has refused the message for good and will not accept an unchanged retry without a change on the sending side. See SMTP 554 across every provider
Outlook bounce questions
›Why is Outlook bouncing my email?
Outlook covers the consumer hotmail.com, outlook.com, live.com and msn.com addresses that sit under Microsoft. Legitimate mail landing in junk usually needs a sender support request, while an IP-level block has to be appealed by whoever controls the IP. Match the exact wording of your bounce to one of the 15 responses on this page to find the specific reason and fix.
›How do I improve deliverability to Outlook?
Authenticate with SPF, DKIM and DMARC, keep your sending IP and domain reputation clean, mail only engaged recipients, and honour unsubscribes. Outlook also publishes postmaster guidance, linked on this page.
