If we put a mailbox on litigation hold in Exchange 2013 (on prem), and we then delete the AD account, is the mailbox preserved? I know there is also the mailbox retention period which is 30 days by default, but after that?

We need to preserve some mailboxes indefinitely for legal reasons, but we also want to delete their AD account for auditor's reasons. Is Litigation Hold the way to accomplish this?

T

If an administrator deletes a user account that has a mailbox, the Exchange Information store will eventually detect that the mailbox is no longer connected to a user account and mark that mailbox for deletion, even if the mailbox is on hold. If you want to retain the mailbox, you must do the following:

1. Instead of deleting the user account, disable the user account.

2. Change the properties of the mailbox to restrict its use and access to the mailbox. For example, set send and receive quotas equal to 1, block who can send messages to the mailbox, and restrict who can access the mailbox.

3. Retain the mailbox until all data has been expunged, or until preserving the data is no longer required.

• Marked as answer by AtlasDan 12 hours 45 minutes ago

Thanks for the quick reply! We'll need to adopt this process. 

If an administrator deletes a user account that has a mailbox, the Exchange Information store will eventually detect that the mailbox is no longer connected to a user account and mark that mailbox for deletion, even if the mailbox is on hold. If you want to retain the mailbox, you must do the following:

1. Instead of deleting the user account, disable the user account.

2. Change the properties of the mailbox to restrict its use and access to the mailbox. For example, set send and receive quotas equal to 1, block who can send messages to the mailbox, and restrict who can access the mailbox.

3. Retain the mailbox until all data has been expunged, or until preserving the data is no longer required.

• Marked as answer by AtlasDan Friday, June 26, 2015 6:40 PM