Please add a short example script which can be used to reproduce this.

No problem, something like that:
<?php
  Header("Content-type: text/plain");
  $inbox=imap_open("{localhost/pop3:110}", "username", "password");
  $total = imap_num_msg($inbox);
  echo "Total: $total messages";
  imap_close($inbox);
?>

What if you use this imap_open() line:

$inbox = imap_open ("{localhost:110/pop3}INBOX", "user_id", 
"password");

Does it work any better? Also, I'd suggest you update
your c-client to imap-2001a.

--Jani

Bad news: your varinat is working like the rest all, and i have imap-2001a ;((

Reread your original comment..there is no problem in connection but with the imap_num_msg() function, right?

Try adding this there:

$arr = imap_check($inbox);
var_dump($arr);

What does it output?

--Jani

object(stdClass)(5) {
  ["Date"]=>
  string(37) "Wed, 24 Apr 2002 23:15:37 -0400 (EDT)"
  ["Driver"]=>
  string(4) "pop3"
  ["Mailbox"]=>
  string(53) "{localhost.localdomain:110/pop3/user="lyubvine"}INBOX"
  ["Nmsgs"]=>
  int(0)
  ["Recent"]=>
  int(4)
}

PHP or c-client is marking all messages as recent even if they are absolutely new. imap_headers is returning an empty array so how can I access headers of messages?

PHP just shows the information it gets with the c-client
functions. So please report this to the c-client author.