Intersect two lists backend

Hello,

I would like to solve how to find same items in two list fields.
E.g.

Old contact
john.smith@gmail.com
beyonce@gmail.com
anymail@test.com

New contact
john.smith@gmail.com
jay-z@yahoo.com
beyonce@gmail.com

Contact (result I want)
john.smith@gmail.com
beyonce@gmail.com

Each data entry has these lists so I need to go row by row ideally with backend workflow to get results into Contact field by modify thing .

How would you do it? I though intersect with:, however I understood this is for frontend?

Thanks!
Pavol

No…

‘Intersects With’ is an advanced filter option, which can be used anywhere you have a list (frontend or backend).