send_confirmation_on_profile_email()
Function: Sends a confirmation request email when a change of user email address is attempted.
Source: wp-includes/user.php:3644
new_user_email_admin_notice()
Function: Adds an admin notice alerting the user to check for confirmation request email after email address change.
Source: wp-includes/user.php:3755
update_option_new_admin_email()
Function: Sends a confirmation request email when a change of site admin email address is attempted.
Source: wp-admin/includes/misc.php:1477