<?php
$mbox = imap_open("{imap.example.org}INBOX", "username", "password")
or die("Can't connect: " . imap_last_error());
$check = imap_mailboxmsginfo($mbox);
echo "Messages before delete: " . $check->Nmsgs . "<br />\n";
imap_delete($mbox, 1);
$check = imap_mailboxmsginfo($mbox);
echo "Messages after delete: " . $check->Nmsgs . "<br />\n";
imap_expunge($mbox);
$check = imap_mailboxmsginfo($mbox);
echo "Messages after expunge: " . $check->Nmsgs . "<br />\n";
imap_close($mbox);
?>