The following steps will guide you through mounting a mailbox for someone who has granted you delegate access to their inbox.
Note: prior to mounting the mailbox to your Outlook Folder List, the user will have had to completed all of the steps outlined in this article: https://support.patriotgis.com/support/solutions/articles/17000081358
Once those steps have been completed, you will follow the guide below:
1) Within your Outlook, click on File > Account Settings and then Account Settings again from the drop-down menu:
2) from the Account Settings menu, click the Change button:
3) From the Change Settings, click More Settings:
4) From the next settings window, click the Advanced tab and then click the Add button and enter the name of the person whose mailbox you want to add (this will not be a search box, be sure to enter the name as it appears in the Global Address List) > Click OK
5)Back on the Change Settings window, click Next:
6) As the final step, click Done and then close the Account Settings window:
You will now see the user's mailbox in your Folder List and be able to click the drop-down error to view the Inbox: