<?php
    $mailList = array("cem@engin.com:şifre", "ahmet@burak.com:şifre");
    foreach($mailList as $row){
        if(strstr($row, "@engin.com")) {
            $sifreKaldir = explode(":", $row);
            echo $sifreKaldir[0] . '<br />';
        }
    }
?>