There are built-in functionalities that help address those scenarios. Retention policies is what you can use for making sure data is preserved for compliance reasons: https://docs.microsoft.com/en-us/microsoftteams/retention-policies Opens a new window
As for reviewing user communications, take a look at communications compliance: https://docs.microsoft.com/en-us/microsoft-365/compliance/communication-compliance?view=o365-worldwi... Opens a new window