Since Magnolia 6.1, OAuth 2.0 is supported but our current implementation works for SMTP Google account configuration. When a user tries to configure SMTP with Office365, he receives an error as follows:

java.lang.RuntimeException: com.google.api.client.auth.oauth2.TokenResponseException: 401 Unauthorized
POST https://oauth2.googleapis.com/token
        at info.magnolia.module.mail.smtp.authentication.GoogleOauthSmtpAuthentication.getAccessToken(GoogleOauthSmtpAuthentication.java:98) ~[magnolia-module-mail-5.5.8.jar:?]

Would be nice to provide a second implementation on Mail module for being able of sending emails using Office365 accounts with OAuth 2.0