To work around this behavior, disable the Deliver messages to both forwarding address and mailbox option in the Active Directory Users and Computers snap-in. To do this, follow these steps:
1. Click Start, click Run, type dsa.msc, and then click OK.
2. Expand domain name, and then click Users.
3. Right-click the user account, and then click Properties.
4. Click the Exchange General tab, and then click Delivery Options.
5. Click to clear the Deliver messages to both forwarding address and mailbox check box, and then click OK.
6. Quit the Active Directory Users and Computers snap-in.
Another reason of this behaviour may be becauce of the delegation feature in Microsoft Outlook.
Delegation: A delegate is someone who is able to speak on your behalf. In Outlook setting up a delegate allows you to control the way a specified person can represent you. You can select someone who has the authority to accept meeting requests on your behalf or actually send out e-mail messages. This time saving feature can help you to delegate things with greater efficiency. Setting Delegates Up
1. From the Tools menu, selection Options.
2. Click on the Delegates tab.
3. Click on ADD.
4. Choose the person and click on Add.
5. Choose the appropriate settings in the Delegate Permissions window and click on OK.
It is strongly recommended that you select ?Automatically send a message to delegate summarizing these permissions? so that your delegate has a reference.
6. Click on OK
The above is the set up a delegate in Microsoft Outlook.
Check in with the CEO’s Outlook if a delegate have been set up for JP. Delete it.
Let me know if it helped.