Dynamic RLS - multiple email formats for staff

I am setting up Dynamic RLS and planning to use the USERPRINCIPALNAME function. However, staff have emails used in outlook which are different than the emails used to share out reports. I want to confirm that I am choosing the correct email to set up the RLS with.

To sign into a Microsoft account and to share the report the email format is [email protected]. And the outlook emails are simply [email protected] . I assume I need to use the [email protected]  emails for security.

My employee table has a column for each email format. I created the CSW_RLS role, and when testing 'View as' with either email type the data filters correctly if I specify what column to use as principal username. E.g., to filter using the locationlocal.ca email I have [Microsoft Email] = USERPRINCIPALNAME(). To filter using the location.ca email I have [Outlook Email] = USERPRINCIPALNAME(). 

How can I be sure which email format to set for the RLS?