How to create anonymous email addrs like Craigs List

It isn't terribly difficult. Go to spamgourmet.com and read about what they do and (a little) how they do it.

The basic bit is that there is a database that maps "what the sender sees" emails to an actual email; and a forwarder that uses that map. Spamgourmet also handles replies (by munging the 'from' field of email that it forwards to you) so your email in reply appears to come from your spamgourmet alias.

well I get the basic understanding that I would setup a mysql dbase table that would have a row where the users real email address is listed in one column and another column where the users anounomous email is listed.

I am thinking I would then create a php script that would do email piping where I would then query the dbase to find the row that matches the anounomus email address to get the persons real email address and then use the php mail() function to forward the emails content to the users real address.

My question I guess really is:
Does anyone know of a tutorial on how to do email piping specifically how to get the email address where the message is going to which is basically the fake email address and also how to get the from email address which is a real email address of the person sending the email and then how to get the body content of the email via php scripting ?

my searches so far using email piping keeps bringing me to tutorials for specific help desk software systems out on the market.

thanks