<p>Note that imap_msgno() doesn't ever give you an error message. So, assuming you're passing about message numbers as a UID, be warned that:</p>
<p>$msguid = false;<br>
$msgno = imap_msgno( $your_initialized_connection, $msguid );</p>
<p>Will leave ($msgno==1) - this is probably not what you want, and it's surprisingly easy to miss while you're doing the basic testing.</p>
imap_mime_header_decode