- preg_match: documentation ( source)
- preg_quote: documentation ( source)
<?php
$user_email = 'asd@toyota.com';
$re_to = "[^@]+@[^@]+"; //"[^@]+@[^@]*toyota[^@]*\.[^@]+";
$re_to = "[.]+";
$regex = preg_quote($re_to, '#') . '$';
$res = preg_match("#$regex#i", $user_email);
echo $res ? 'True' : 'False';