To enable XOAUTH2 (ie for O365), you can replace file "IMAPProtocol.php" in folder "/plugins/EmailReporting/core_pear/Net" by the one available in this repository
Modifications done:
Line 41: adding "XOAUTH2" method
Line 561: adding "XOAUTH2" switch case
Line 729-797: function to authenticate with OAUTH on O365
To obtain your tenantId & clientId, you can follow (dont have a look on PHP sections) : https://vielhuber.de/en/blog/access-with-php-to-exchange-office-365/
Or
https://learn.microsoft.com/en-us/entra/identity-platform/quickstart-register-app https://learn.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth#use-client-credentials-grant-flow-to-authenticate-smtp-imap-and-pop-connections
Then, on Mantis EmailReporting configuration, set Username as following format : {email}|{tenantId}|{clientId} (separator : pipe)
And select "XOAUTH2" on Authentication method
Enjoy !