We recently ran into similar discussion on StackExchange regarding Office 365, so we felt like we need to share our knowledge.
Indeed, there are two cases in which you’ll be able to re-store a deleted mailbox in Office 365.
First – if a mailbox has been deleted recently and it is still on 30 days retention period. Here’s how to do that.
Second – even if the retention period has passed the mailbox can still be recovered if inactive mailboxes was on when you deleted the mailbox.
Although, a much easier way is to use UpSafe Cloud Backup for Office 365.
Using our solution you’ll never have to worry about the loss of data, namely emails, contacts, calendar, even OneDrive and SharePoint.
Our backup is cloud-based, so even a large-scale loss of data on local PCs in your office won’t affect it.