Validates a user's email address.
Checks that a user's email address exists and follows all standard validation rules. Returns error messages when the address is invalid.
$mail: A user's email address.
If the address is invalid, a human-readable error message is returned. If the address is valid, nothing is returned.
function user_validate_mail($mail) {
if (!$mail) {
return t('You must enter an e-mail address.');
}
if (!valid_email_address($mail)) {
return t('The e-mail address %mail is not valid.', array(
'%mail' => $mail,
));
}
}