A Users meetings gets automatically sent to shared mailbox

Question

Hi,

We have an issue in our company that every meeting for a user gets automatically forwarded to a shared mailbox that the user used to have access to.

All of the users privileges have been revoked for the shared mailbox (both in AD, on-prem and in exchange admin), there are no set rules or delegations on either server side or client side that should cause this behaviour and I've even tried suspending the users account for a short period of time. Nothing has helped.

Could there somehow be a hidden rule somewhere that causes such a behaviour? And how do we find it?

Sorry for any grammatical errors, English is not my native language and our Office products are in Swedish, so if anything is amiss I apologize.

Answer 1

Hi @Rebecka Fors ,

Thanks for your feedback above which shared more information and glad to know that your issue is resolved now! Since our forum has the policy that The question author cannot accept their own answer. They can only accept answers by others, and according to the scenario introduced here: Answering your own questions on Microsoft Q&A

I would make a brief summary of this post so that other forum members could easily find useful information here:

[Activating lagged copies - Summary]

Issue Symptom:

Every meeting for a user gets automatically forwarded to a shared mailbox that the user used to have access to.

Solution:

Check for hidden inbox rules with the Get-InboxRule command:

C:\> Get-InboxRule -Mailbox ******@domain.com -IncludeHidden

Reference Link:

https://supertekboy.com/2021/07/21/former-calendar-delegate-still-receives-meeting-notifications/(Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)

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You could "Accept Answer" for this summary to close this thread, and your action would be helpful to other users who encounter the same issue and read this thread. Thanks for your understanding!

Answer 2

Hi Rebecka, does this only happen for meeting requests? If so, the most likely culprit is the ResourceDelegate setting on the mailbox, which you can check via:

Get-CalendarProcessing ******@domain.com | select ResourceDelegates

If it also happens for regular emails, it's likely some other form of forwarding. Have you made sure that all server-side components are covered, including forwardingAddress, forwardingSMTPAddress, transport rules?

Answer 3

Hi @Rebecka Fors ,

Agree with @Vasil Michev , did you try to check by the above command, apart from that you can also consider other possible reasons:

1. Mail Flow Rules Set by Admin: Check if any mail flow rules have been set up by your administrator. Sometimes, these rules can inadvertently cause automatic forwarding of meeting invitations or events. You can contact your admin to verify and review the rules in the Exchange admin center.
2. To further figure out the problem, please contact admin to run a message trace for the specific mail flows.

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Answer 4

Hi!

We solved the issue with the following powershell script. This told us our user had a hidden rule and we could delete the identity with Remove-InboxRule

C:\> Get-InboxRule -Mailbox ******@domain.com -IncludeHidden

Answer 5

Hi!

We solved the issue with the following powershell script. This told us our user had a hidden rule and we could delete the identity with Remove-InboxRule

C:\> Get-InboxRule -Mailbox ******@domain.com -IncludeHidden