Listserv functionality catchall or not?

I am looking to create a listserv functionality for my website in the style of 开发者_运维问答google groups. That is, someone creates a group and thus, a group email address is born. Should i be using a catchall or should i come up with some way to automatically create a mailbox when someone creates a group?

That really depends on your mail server setup. Your mail server might allow the easy ad hoc account creation, or it might not.

Have you considered using any of the widely-used open source programs (e.g. Mailman) that do exactly what you are describing instead of rolling your own? I would consider it, because people tend to expect mail to work in a particular way, and get a bit upset if it doesn't.