Office 365: How to handle resign user mailbox with litigation hold enabled?

Litigation hold is a feature that allows you to keep your mailbox with specific period or unlimited period. However, this is only the high level definition of litigation hold. Through out my deep and many research of Microsoft articles, especially technet it only state high level of definition of litigation hold but nothing about notices.

Few weeks ago I’ve encounter one of my user reported to me, saying that they have a user account that is disable (in Active Directory), blocked sign in and unlicensed but the mailbox still in active state and able to send (etc inbox forwarding rules) and receive mails and also able to login if with full access. After few research, I found a Microsoft article (support article “https://support.office.com/en-us/article/manage-inactive-mailboxes-in-office-365-296a02bd-ebde-4022-900e-547acf38ddd7“) , about how to handle inactive mailboxes. However, it still didn’t state why it happens or how this mechanism works.

We call this as deprecated account but active mailbox. I really hope that Microsoft could do something about this as it seems to me it is pretty troublesome to go extra further step to handle this, and also hope that they could elaborate more about litigation hold pro and cons or how this mechanism works.

*Note:

Please take note if you have mailboxes with unlimited litigation hold enabled, and user account in Active Directory is disable but in a sync Organization Unit, please move them to a unsync organization unit IMMEDIATELY or else it will full up the mailbox storage. 

To check whether which Organization unit is unsync;

1. Just go to your Azure Active Directory Server
2. Windows Start button
3. open MIISCLIENT or Synchronize Services
4. On top select “Connection”
5. double on your local domain
6. select Configure Directory Partition
7. at the bottom right button
8. select “Containers”
9. enter Azure Active Directory credential
10. you will able to view unchecked boxes means they are the unsync organization unit.

 

References:

1. https://support.office.com/en-us/article/manage-inactive-mailboxes-in-office-365-296a02bd-ebde-4022-900e-547acf38ddd7
2. https://technet.microsoft.com/en-us/library/ff637980(v=exchg.160).aspx#lithold
3. https://technet.microsoft.com/library/dn743673(v=exchg.150).aspx
4. https://technet.microsoft.com/en-us/library/dn790612.aspx