<!-- Collection of code snippets by Arne Vajhøj -->
<!-- posted to eksperten.dk, usenet and other places (2002-now) -->
<?php
$_SESSION['MitArray'] = array();
$_SESSION['MitArray']['1'] = array("User"=>"Brugernavn", "email"=>"min email", "postnummer"=>"8800");
$_SESSION['MitArray']['2'] = array("User"=>"user", "email"=>"min email", "postnummer"=>"8812");
$_SESSION['MitArray']['3'] = array("User"=>"user", "email"=>"min email", "postnummer"=>"8800");

$ma8800 = array_filter($_SESSION['MitArray'], function($v) { return $v['postnummer'] == '8800'; });

print_r($ma8800);
?>