Using IMAP () in PHP to get recent unread emails count
/* connect to gmail */
$hostname = '{imap.gmail.com:993/imap/ssl}INBOX';
$username = 'user@gmail.com';
$password = 'user_password';

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

$recent_emails = imap_search($inbox,'RECENT');
if ($recent_emails)
   echo count($recent_emails);
else
   echo "false return";
imap_close($inbox);

$check = imap_mailboxmsginfo($inbox);
if ($check)
    echo "Recent: "   . $check->Recent  . "<br />n" ;
else
    echo "imap_check() failed: " . imap_last_error() . "<br />n";
imap_close($inbox);

$status = imap_status($inbox, $hostname, SA_ALL);
if ($status)
  echo "Recent:     " . $status->recent      . "<br />n";
else
  echo "imap_status failed: " . imap_last_error() . "n";

$recent_emails = imap_search($inbox,'NEW');
if ($recent_emails)
   echo count($recent_emails);
else
   echo "false return";
imap_close($inbox);

Recent flags on messages.

$inbox = imap_open('{imap.gmail.com:993/imap/ssl}INBOX','user's email id','user's password') or die('Cannot connect to Gmail: ' . imap_last_error());
        $unread_emails = imap_search($inbox,'UNSEEN');
        $emails = imap_search($inbox,'ALL', SE_UID);

if ('email_max_uid') = 0
        $recent_mails_count = count($unread_emails);
    else
        $recent_mails_count = max($emails) - Array['email_max_uid'];

echo count($recent_mails_count);