We have E3 licences for all our users, with archiving enabled (if that matters).
We would like to keep access to our ex-employees' mailboxes in perpetuity, but as cheaply as possible. Aside from moving old mailboxes to cold storage, what are our options? I was told by someone knowledgeable in the area that even unassigning an E3 licence will keep the mailbox intact in Exchange Online. So, I called Microsoft to confirm, and they tell me no, that's not correct. 30 days is the max they guarantee recovery for. So I sent her a Microsoft URL that states this:
"Caution: When a user’s license is removed, all data that is associated with that user account is held for 30 days. After the 30 day grace period, the data is deleted and can’t be recovered, except for documents that are saved on SharePoint Online and the data in the user's mailbox. The user mailbox will remain in Exchange Online until it is deleted, permanently removed or purged by the Office 365 admin. You can reassign a license to the user and make the mailbox active again."
So I was left with little confidence that the support staff had any clue about this issue.
Does anyone know for sure? The paragraph above is very confusing too: "we delete all data except files and mailboxes." What's left?!