How to access the mail archive of a user that is no longer in the Active Directory?

How can the mail archive of user that is no longer the Active Directory be accessed?

The administrator needs to assign the E-mail Alias to another User. This can be done under: Webinterface -> Administration -> Users and Groups -> E-Mail Addresses
Another way is to use configure a deputy policy in the admin webinterface.
With version 2032 it is possible to select "Enable Group Addresses" for Active Directory Authentication Servers in the advanced tab of the Realm Konfiguration.
This way, the user has Access to all alias addresses that are configured via groups in the active directory
These addresses can then be selected in the Userinterface,Webinterface,Outlook Addin or Mobile App via Maildepot -> "Select deputy" and be used for Maildepot queries