Where does the mail app store its auth data?

Hey guys!

I am setting up a next cloud for our project group to simplify collaboration.
Our group is divided in sub groups and every sub group gets an own e-mail-adress.
So, when I am in sub team 1 and 2 my nextcloud account should be logged in 1@mail.com and 2@mail.com.
I know that I can log in uses to an e-mail-adress which includes their username but a login by group isn’t possible. But couldn’t I copy the login data to each sub group member manually?
For this I need to know, where those information are stored … in the database or in a file?
I hope for some answers!

Best wishes,

As far as I know, the credentials are stored in the Nextcloud database.
There are several tables with the mail concerning data.

Yes, that was easy. I haven’t seen this table…