Environment: Exchange 2013 and Outlook 2013

We have two shared mailboxes, several users have the mailboxes open in their outlook 2013 profiles. 

Every time an email is sent to one of the mailboxes, it is forwarded/moved to the other shared mailbox. 

Troubleshooting steps taken: 

1. I've tried creating new Outlook profiles for each mailbox, then running 'Outlook /cleanrules' from the cmd prompt, this successfully clears all rules.
2. I've tried logging into each mailbox via OWA and there are no server side rules present.
3. I've asked users if they have any rules set, naturally, no one has any information unfortunately. 

This leads me to believe that one of the users that has access to the mailbox either has a 'client-side rule' set to move the message or is manually 'dragging and dropping' the message into the other mailbox. 

How can I find out how or who is moving the messages? 

Unless you have configured the shared mailboxes as additional accounts in Outlook, you will not be able to manage the rules there. Best check with PowerShell:

Get-InboxRule -Mailbox shared

For forwarding, make sure to check both the ForwardingAddress and the ForwardingSmtpAddress. Check for any Transport rules as well. Also do a message trace, it should show some relevant info. If you still cannot find anything, enable Auditing with AuditOwner, if it's a client action it should be captured there.

Hi,

As Vasil suggested, please check if there is any transport rule to forward messages sent to these shared mailboxes. Also, you can use the following cmdlet to disable the forwarding for shared mailbox.

Set-Mailbox -Identity "shared mailbox" -DeliverToMailboxAndForward $false

Hope this can be helpful to you.

Best regards,

Amy, Vasil, thanks for your help... Those are some more things Ill look at. I have not yet. Ill post my findings. Unfortunately I feel a user has a rule set up... :-(