- preg_match: documentation ( source)
- preg_quote: documentation ( source)
<?php
$user_email = 'asd@toyota.com';
$re_to = "[^@]+@[^@]"; //"[^@]+@[^@]*toyota[^@]*\.[^@]+";
$regex = preg_quote($re_to);
$res = preg_match($regex, $user_email);
echo $res ? '1' : '0';