[Mailman-Users] Adding extra information to subscription requests.

[I originally sent this to -developers but that was probably the wrong
place. If you see it there, please respond here instead.]

This is a project I've been noodling about with for a bit but now is the time
to ask how to do it properly.

For a mailing list I run using 2.1.9 I would like to new subscribers to provide
an explanation of why they would like to join the list and acknowledge their
acceptance of the list code of conduct.

Now adding a textarea and checkbox to the subscription form is easy but how do
you make that extra information get sent to the list owners? Do I have to hack
cgi-bin/subscribe or is there some simpler way?