In our company, we have implemented the logic whereas users get disabled and after 90 days the users are then deleted from Active Directory all together.
We need to understand the actions done on the user's Exchange account, when the AD account is deleted
Release : 14.x
Component : IdentityMinder(Identity Manager)
Identity Manager's Active Directory connector only deletes the AD account when the user is deleted. It doesn't perform any mailbox related operations.
When the AD account is deleted, the mailbox will be moved to a disconnected list as per https://docs.microsoft.com/en-us/exchange/recipients/disconnected-mailboxes/disable-or-delete-mailboxes?view=exchserver-2019 Subsequently, the mailbox is deleted permanently as per the AD mailbox retention policy.
If additional steps are required on the mailbox (ie delete / disable) – you might want to implement the logic shared via https://knowledge.broadcom.com/external/article?articleId=116295 (either using PX / Custom exit etc) – but ideally, this would all be handled centrally by the DC itself.