Bagaimana mengatasi error pada imap_search ?

Bagaimana mengatasi imap_search yang tidak menampilkan semua email ?

Email yang ditampilkan berasal dari mail server.

Beberapa email berhasil view, tapi sebagian lagi tidak berhasil.

Berikut potongan program yang saya buat :

<?php
	$host 			= '';
	$user 			= '';
	$password 		= '';
	$conn 			= imap_open($host, $user, $password) or die('unable to connect : ' . imap_last_error());
	switch ($cond) {
		case 0: $cond 	= 'ALL'; break;
		case 1: $cond 	= 'SEEN'; break;
		case 2: $cond 	= 'UNSEEN'; break;
		default: $cond 	= 'ALL';
	}
	$mails 			= imap_search($conn, $cond);
	echo '<ul id="" class="list-unstyled">';
	if ($mails) {
		rsort($mails);
		foreach ($mails as $read) {
			$headers 	= imap_fetch_overview($conn, $read, 0);
			if ($headers[0]->seen == 1) {
				$liStyle = ''; $lbStyle = 'style="border-color: #4139ad"';
			} else {
				$liStyle = 'class="unread"'; $lbStyle = 'style="border-color: #63e667"';
			}
	?>
	<li <?=$liStyle?>>
		<a href="">
			<i class="mail-label" <?=$lbStyle?>></i>
			<div>
				<p class="m-none"><?=substr($headers[0]->from, 0, 20). '...'?></p>
			</div>
			<div class="col-mail">
				<p class="m-none mail-content">
					<span class="subject"><?=$headers[0]->subject?></span>
				</p>
				<p class="m-none mail-date"><?=date("F j", strtotime($headers[0]->date))?></p>
			</div>
		</a>
	</li>
<?php
		}
	} else {
		echo '<li>No data available</li>';
	}
	echo '</ul>';
	imap_close($conn);
?>