FORM POST Operation Invisible To Users

We've got a webserver with an ASP application on it that needs to be able to send e-mails when certain actions are performed. However, due to a funky network setup, the server is (and will continue) to be unable to send mail via SMTP, so, in the meantime, what we want to do is redirect the mail message to a formmail.cgi script on a Unix box.

Now, the e-mails have to be dynamic, so hard-coding scripts is out of the question, and there's no way the Unix box can talk to the database on the IIS box (It's a long, convoluted story, but that's the way it is). So, my question is, does anybody know off the top of your head what the protocol is for doing an HTTP-POST operation behind the scenes? Ideally, I want to write one global SendMail function, and just pass the Name/Address/Message variables into it.