You could do that with CDO for NT. For detail usage of CDO for NT, check with the book from Wrox: Professional ASP 2.0 on Page 658. I haven't tested the codes, but it should work with some minor modifications.
To use CDO for NT in PHP:
$my_inbox = new COM("CDONTS.Session");
To connect to the mail box:
$my_inbox->logonSMTP($username, $email_addr);
Hope it can help. =)
