Outlook deleting emails automatically

Question

We have a Generic mailbox , which is being used by around 10 users and they USE VDI machines to access the mailbox in Outlook.
Outlook is constantly deleting emails from the mailbox and I am not able to identify exact user as they are using it with Generic Mailbox Username/password, so even in the Audit Logs it shows the Mailbox Username and even the IP is also a problem as its giving the Gateway IP ,because its a VDI machine.

They are escalating this as they are using the mailbox for Customer Service where in ,email comes to this mailbox and it is forwarded to a SAP server for creation of requests.

Any help would be appreciated, as I am not able to identity from whose outlook its happening .

Answer 1

Remove the ability to access it with a generic username and password. There is no way to identify who is deleting it if you allow that.
In other words, disable the shared mailbox AD account.

Then, delegate access ( full access and send as if needed) to the users who need access:
https://learn.microsoft.com/en-us/exchange/recipients/mailbox-permissions?view=exchserver-2019

Then ensure auditing is enabled for all actions for that mailbox.

https://learn.microsoft.com/en-us/exchange/policy-and-compliance/mailbox-audit-logging/enable-or-disable?view=exchserver-2019#configure-mailbox-audit-logging-settings-for-administrator-delegate-and-owner-access

Answer 2

Do you access email on any other devices?

I've had users report similar issues to me in the past and what they were seeing is Outlook resyncing with the server when they open it. They saw messages they had deleted/moved on other devices - cell phone, home computer, etc. - and their office Outlook just updating.

Answer 3

Sorry for the delay, as per the suggestion, i have converted the mailbox to Shared and gave the users access.
Lets see, if they come back.