[Mailman-Users] subscribe users by email from list admin?

[Matt Morgan]

Is there any way, in mailman, to subscribe a user (or users) via an email
from an email address other than the one being signed up?

E.g., I imagine a simple online form, including an email entry field, that
fires off an email upon successful submission, that subscribes that user to
a list. But I can't set the from: address of this email to the subscriber's
address. I can set it to a list-admin address, if that helps.

By the way, I realize there are commands in /bin that do the equivalent. As
far as I know, I can't easily get the place I have the online form
(Wufoo.com) to kick off those commands.

Thanks,
Matt