Problem s mail() i Windows 2K

Zdraveite,

Imam edin problem, koito ne moga da sboria...
Do sega vinagi sum polzval razni 3rd party clasove za prashtane na
mail prez SMTP, no naskoro reshih da se opitam da polzvam mail()
funkciata na PHP.
Za sujalenie, kakvoto i da pravia poluchavam edin i sushti warning:

-------------------------------------------------------------------
Warning: mail(): SMTP server response: 451 See
http://pobox.com/~djb/docs/smtplf.html. in C:\bla\bla\mail.php on
line 42
-------------------------------------------------------------------

Rovih iz vsichki RFC's, svurzani sus SMTP i otkrih che error-code
451 oznachaval problem, nezavishesh ot men, nai-veroiatno SMTP
servera ne funkcioniral v momenta, da sum probval pak sled
izvestno vreme ;(
V sushtoto vreme, kato opitam da pratia mail ot mail-clienta si,
v moia sluchai The Bat, na koito mu e posochen sushtia SMTP server
niamam nikakvi problemi - priema si maila.

Niakoi sbluskval li se e s podoben problem? Shte sum blagodaren
na vsiakakvi idei i preporuki!

Pozdravi,

Atanas Vasilev

ENVIRONMENT:

PHP 4.3.8 SAPI (php4apache2.dll)
APACHE 2.0.50
WINDOWS 2000 Professional 5.00.2195 Service Pack 4


php.ini

    [mail function]
    ; For Win32 only.
    SMTP = mail.ultima-bg.com
    smtp_port = 25

    ; For Win32 only.
    ;sendmail_from = [email protected]
    ;polzvam ini_set("sendmail_from", "[email protected]");
    ;na baza script

    ; For Unix only.
    ;sendmail_path =



phpinfo()

    Internal Sendmail Support for Windows  enabled