MAIL() Problem with NT4.0 IIS

Hello, I have a problem sending mail via the mail() function. When I call mail() the server doesnt answer anymore. I just get a browser timeout. mail("erik@wwww.at", "Testmail", "Test.", "From: ab@send.er\nReply-To: devnull@koehntopp.de"); I also tried: mail("erik@wwww.at", "Testmail", "Test.") Configuration: PHP3 IIS4.0 NT4.0SP6a I am running merak mail server on my machine. PHP3.ini: [mail function] SMTP = mail.wwww.at ;for win32 only (Local Domain on my Mailserver) sendmail_from = erik@wwww.at ;for win32 only sendmail_path = ;for unix only, may supply arguments as well (default is sendmail -t) I also tried localhost or other external mail servers but none of them worked. Are there any special settings I have to consider in IIS? It would be really great if someone could help me. Thanks Erik