Getting the domain and Userid part from an email address

$em="mynam@domain.com";
$ar=split("@",$em);
echo $ar[0];
echo "<br>";
echo $ar[1];

$em="mynam@domain.com,second@second.com,
third@third.com,fourth@fourth.com";

$ar=split(",",$em);

while (list ($key, $val) = each ($ar)) {
$ar2=split("@",$val);
echo $ar2[0];
echo "<br>";
echo $ar2[1];
echo "<br><br>";
}