- substr: documentation ( source)
- explode: documentation ( source)
<?php
$email = "h@hotmail.com";
$em = explode("@", $email);
$name = $em[0];
echo ((strlen($name) > 3) ? substr($name, 0, 3) : "*") . "@$em[1]";
$email = "hag@hotmail.com";
$em = explode("@", $email);
$name = $em[0];
echo ((strlen($name) > 3) ? substr($name, 0, 3) : "*") . "@$em[1]";
$email = "verylongemail@hotmail.com";
$em = explode("@", $email);
$name = $em[0];
echo ((strlen($name) > 3) ? substr($name, 0, 3) : "") . "*@$em[1]";