/* connect to gmail */
$hostname = '{imap.gmail.com:993/imap/ssl}INBOX';
$username = 'xxxxx@gmail.com';
$password = 'xxxxx';

$inbox = imap_open($hostname,$username,$password) or die('Cannot connect to Gmail: ' . imap_last_error());

/* grab emails */
$emails = imap_search($inbox,"RECENT");

/* grab emails */
$date = date ( "d-M-Y", strtotime ( "-3 days" ) );
$search = 'SINCE  "'.$date.'"';
$emails = imap_search($inbox, $search);

Notice: Unknown: Unknown search criterion: SINCE (errflg=2) in Unknown on line 0