When discovering tenant users, by default, the email information is obtained the from the email address attribute of the AD user. You can configure your tenant environment to obtain the email information from the User Principal Name (UPN) of the AD user. UPN is the name of the AD user in an email address format.
From the navigation pane, go to Manage > Companies.
The Companies page appears.
Click a company name.
The company details page appears.
Under General, move the Use UPN instead of e-mail toggle key to the right.
An authorization code is generated for the company.