Forum Discussion
Preventing Users from deleting emails from O365 Group Mailbox
How can I limit users for subject issue? I need kind of Read Only access to all users.
You cant, Groups are not designed to offer read-only access. You can ensure that messages are not permanently deleted by enabling retention policies/hold on the Group, but that will still allow users to perform the delete action in Outlook/OWA.
Take into account that for retention policies you need Exchange online plan 2 and if you include Office 365 groups in a retention policy, both mailbox and site contents are retained.
https://support.office.com/en-us/article/overview-of-retention-policies-5e377752-700d-4870-9b6d-12bfc12d2423