If you are using Office 365, from October 1st. 2022 notifications and ticket creation by email will no longer work in iTop.
All notifications configuration steps are described in our documentation.
If you use Mail to ticket automation, you should deploy the version 3.6.0 of this extension on an iTop 2.7.7 or 3.0.2 and use OAuth 2.0 authentication, as described in the documentation.
For further questions, please contact your Microsoft support.