What's the best way to set up a temporary group blog?

This might not even be possible but hey, it’s the Internet. I want to set up a collective, temporary (a few weeks) blog for anyone to contribute to. Ideally, people would send an email to something like post@blogname.hostname.com and it would automatically post.

I wouldn’t be able to enter everyone’s e-mail manually.

Can anyone suggest a service that would make this possible? Thanks!