This knowledgebase article will guide you through the process of adding a user alias to an existing Exchange 2016 mailbox.
Accessing the Exchange Panel
In the Mailprotector Console, navigate to //Domains/$domain/Users, and click on the "Manage Exchange Button"
Adding a User Alias
In the Exchange Panel, select Users from the right hand menu.
Click on the Display Name of the user you wish to modify.
From the email menu, select Edit
You can add one or more aliases via the "Modify Email Aliases" field
Once finished, click the button.