The user registers someone else's mail, how to respond?

Question

User identification

How registration works for me:
The user registers (mail, password, password repeat),
then a verification letter arrives, you need to confirm, after which you can log into your account.

When a user, when registering, does not specify his mail, registers another person who will encounter an error during registration "This email address is already in use by another user", but he will receive a verification letter in the mail, if he confirms, he will be able to log in, but how to convey it And is it correct to use this approach?

Answer 1

You don't have to bring anything anywhere. In this case, he will use the "reset password" link.

Answer 2

Confirmation is required when switching to a verification email:

1. e-mail or username;
   
2. the password that was created during registration.