Manual:ResetUserEmail.php/en

Details
resetUserEmail.php file is a maintenance script to change the email address of users on the wiki, and mark the email address as confirmed. In addition to that, it will set a random password on that account. This will require the user to reset his/her password in order to be able to login again.

This can be used to set or change an email address on an account that doesn't have a confirmed email address or the email address is no longer accessible. This can also be used to effectively lock an account by setting the email address to a fake one, since it also resets the password.