- var_dump: documentation ( source)
- explode: documentation ( source)
- preg_grep: documentation ( source)
<?php
$input = "michael@test.com dave@cheese.mansions milkman@serverdouche.co.uk";
$email = preg_grep("/[-0-9a-zA-Z.+_]+@[-0-9a-zA-Z.+_]+\.[a-zA-Z]+/", explode(' ', $input));
var_dump($email);