I need to create a test to prove that the 5000 list item limit can be exceeded. More specifically Users. I have en Excel spreadsheet that contains 5002 users. I don't need the trivial data to be included, just name and work email. With CSV files, the limit is 250 and I cannot add the work email to it. I have looked at some powershell scripts but with my lack of experience with it, I can't seem to get it right.
So to be clear the question is
(How)Can I import 5002 users with a custom work email address?
EDIT: Up till now I've tried:
Looking at a console app but UserProfiles in SPO are read only when accessing them via CSOM
Powershell scripts so far are all for SP2010 or SP2013 and don't work for online