RLS external user userprincipalname

Hi 

I have a report that needs to be shared with external users and they can only see their own data. So I have set up a RLS with userprinciplename(). The filtering goes through company and emails that belong to that company, stored in excelfile so it can be updated when there is a new company or user is coming in.

Which emailaddress should I use for in the excelfile, the normal emailaddress or the emailaddress with prefx #EXT# that can be found in the service under security - add or give permission to app, --> basically the emailaddress that is known in admin?!