Microsoft 365 / WiscMail / WiscMail Plus - Understanding SMTP errors

This information in this document is intended for email administrators or campus mass emailers who are seeing errors when sending email smtp.wiscmail.wisc.edu. If you are a non-Office 365 user and are experiencing these errors, then please contact your email administrator. If you are a Microsoft 365 user and are seeing these errors in your email client please contact the DoIT Help Desk for assistance.


Keywords:
office 365 o365 m365 microsoft 365 5.7.1 550 5.2.4 5.1.8 5.7.1 5.2.3 5.1.4 5.5.1 5.7.0 must use tls not allowed to send email postmaster address unknown or illegal alias invalid host return failed bad reputation message exceeds local policy violation size limit hop exceeded mail loop service account netid proofpoint proof point
Doc ID:
3998
Owned by:
O365 S. in Microsoft 365
Created:
2005-09-07
Updated:
2025-01-29
Sites:
DoIT Help Desk, Microsoft 365