Thank you for posting your query on Microsoft Q&A, from above description I could understand that you are looking for email notification for any configuration changes in the Microsoft defender / M365 security portal.
Please do correct me if this is not the issue by responding in the comments section.
Currently we don't have any email notification trigger option to report policy/setting changes for Microsoft defender portal, however you may access the audit reports to review any changes.
- However, if this is impacting your business requirements then I would recommend to post this on our feedback portal which has visibility to the dev team.
Please "Accept the answer (Yes)" and "share your feedback ". This will help us and others in the community as well.
Thanks,
Akshay Kaushik