[Mailman-Users] Auto Subscribe

[Angel Gabriel]

Is it possible to have users automatically subscribed to my lists? I found
that a lot of people do not understand how to send commands via email, and
it is not possible for people to access my webservers at the moment.
Basically, I would like to create the following scenario.

User sends email to a address I set up.
User gets subscribed to mailing list.

I'm not worried about spoofed addresses, or bouncing addresses, or abuse.
The people this list are for, can just about work thier mobile phones. Any
help would be appreciated.