[bug]: Email is register-sensitive

[KatyaGolyagina]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

login by email is register-sensitive, i wait that Test@fake.com will be same test@fake.com, but it isn't

Steps to reproduce

1. login at test@fake.com >> one new user appeared in the admin panel
2. logging in at Test@fake.com >> 2nd user appeared in the admin panel.
   FR: received two e-mails to the same e-mail address and there are two users in the system
   Expected result - both logins will be ones user in the system

Environment

Production

Version

Self-hosted