Test IMAP connection

imap.php

<?php

$mail_server = "mail.example.com" ;
$mail_username = "user@example.com" ;
$mail_password = "a very long and unbreakable password" ;

$mail_port = 143 ;
$mail_folder = 'INBOX';

echo "<h1>".$mail_username." on ".$mail_server."</h1>\n\n" ;
$mbox = imap_open("{".$mail_server.":".$mail_port."/imap/novalidate-cert}".$mail_folder, $mail_username, $mail_password) or die("Error opening mailbox: ".imap_last_error());
$mailboxheaders = imap_headers($mbox);
if ($mailboxheaders == false) {
    echo "<p>".$mail_folder." is empty.</p>\n\n";
} else {
    echo "<h2>".$mail_folder."</h2>\n" ;
    echo "<ol>\n" ;
    $msgno = 0;
    foreach ($mailboxheaders as $val) {
        $msgno++;
        echo "  <li>".$val ."</li>\n";
    }
    echo "</ol>\n\n" ;
}
imap_close($mbox);