Problem:
- Microsoft Outlook continually prompts you for a username and password for your Exchange account, but will not accept your authentication credentials.
- You may also be using Kaspersky, Bitdefender, or another antivirus/firewall program
Solution:
- Update the windows registry with values as described in this Microsoft article: https://learn.microsoft.com/en-us/exchange/plan-and-deploy/post-installation-tasks/security-best-practices/exchange-extended-protection?view=exchserver-2019#ntlm-version-requirements
- Create a network exception in Kaspersky Anti Virus for the mail server "ex.mail.ovh.ca" as described in this Kaspersky forum discussion: https://forum.kaspersky.com/topic/kaspersky-blocking-microsoft-outlook-on-exchange-servers-with-windows-extended-protection-wep-28665/
