mail to authenticated smtp on WIN2K

Hi, I've tried the following script: <?php mail("myaddr@provider.com", 'Subject', 'Message', "From: myaddr@provider.com"); ?> on PHP 4.1.2-32 with Apache on a Win2k machine. The ISP smtp is known as "smtp" in the Outlook send server acct and the smtp server requires requires authentication. If I ping it, I get the real smtp name, let's say ssmtp.domain.com, so I tried in php.ini (at the system dir): SMTP = smtp sendmail_from = myaddr@provider.com or SMTP = ssmtp.domain.com sendmail_from = myaddr@provider.com Neither option makes the above script work. Nor the numeric IP address itself. I get "Server Error" response. I suspect this is because of the authentication requirement. If this is so, is there a way to specify this authentication either in php.ini or in the script? Any input is greatly appreciated. Thanks. Rodrigo