I've noticed a difference in appearance with how Outlook appears and working with Rules.  One of our users sent me the following screenshot:

To my knowledge, this is the only user that can toggle between different mailboxes like this.  In this screenshot, she can toggle between 6 of them.  I tried enabling this for myself and was unable to duplicate seeing multiple mailboxes with a drop-down box..  I already have full access to 3 mailboxes and I don't see this for rules.  I tried adding a second and third mailbox to my profile keeping my personal as default.   I still didn't see the drop down option available.

If anyone can provide some insight to how to enable/disable this, it would be appreciated.

Hi,

Based on my knowledge, if you create a new Exchange account in Outlook with different profiles from your primary mailbox, then the rule can be created for different mailbox account. For example:

When we create a rule, there are two accounts for choosing:

Therefore, please setup your shared mailbox with different data file in Outlook then check whether the Inbox rule can be created for different accounts.

Regards,