Delegates often process Outlook email for others. It’s a feature that works well. That is, until protected email arrives. Delegates shouldn’t be able to read protected email in other peoples’ mailboxes. But some versions of Outlook allow this to happen. If you want to be sure that delegates can’t access protected email, maybe you should consider using a dual-mailbox approach.
https://office365itpros.com/2022/02/22/outlook-email-private/
