bbs.spamgourmet.com

Sorry.

If you would be interested in subscribing to a commercial version of spamgourmet with service garantees, send a email to:
wouldbeclient.20.emphyrio (at) spamgourmet. This guy is looking at creating such a service. Tell him Syskoll sent you.

Here's an idea (this is what sneakemail does to control his bandwidth costs): provide the mail forwarding as requested, but up to some rate (e.g. __ MB/month). Paying subscribers get more/unlimited bandwidth. This isn't foolproof since people can still get their mail by signing up for multiple spamgourmet accounts and using another mechanism to get their mail forwarded to their main account, but if people have that ability already, they probably have enough knowledge and resources to do without spamgourmet. (You'll have to disallow the user+someword@domain patterns, which is the only easy way I can think of to get around this restriction. Maybe you already do that.)