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If you delete an item in your mailbox, it will enter the deleted items folder. This is like the recycle bin on a Windows desktop computer and the email hasn't actually been deleted yet, it has simply been put into a sub-folder named deleted items. Periodically it is a good idea to empty your deleted items folder to clear out these old emails and get back space in your mailbox. When you do this, any email in the deleted items folder will be removed from view and marked for deletion. Our email servers will not actually delete these items at this stage, they will be held for a period of time according to our delete item retention policy. This is currently a period of 90 days before it is purged from the mailbox database permanently.
Please note, If you have an archive mailbox that is disabled/deleted, it can be reconnected to your primary mailbox within 30 days of disabling it. In this case, the original contents of the archive mailbox are restored. After 30 days, the contents of the original archive mailbox are permanently deleted and can't be recovered. So if you re-enable the archive more than 30 days after disabling it, an entirely new archive mailbox is created. Please bear this in mind if you think you may require contents from an archive after it is disabled/deleted.
Backup of the email environment
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