[Exim] Let the user manage emails

Hello,
I plan to rent my own server with a couple of friends. Managing should not be
done with a webinterface like Webmin or Confixx, but with a SSH shell access
by ordinary users. Each user is managing a virtual domain with one or more
email adresses.
The way of emails should be like that:

external clieant via SMTP -> MTA (exim) -> MDA (maildrop) -> Maildir in the
users homedir.

My problem are how to enable the users to create email adresses with config
files in their homedirs. I need to place a aliases and virtual table in the
users homedir which in only for one virtual domain.
My second is how to tell the MDA (maildrop) which email is the original
recipient, since one user has more than one email adress. (maybe with adress
extension (+) and give this as a parameter to maildrop?)

A idea:
Using a file like that as a virtual map: (for local user example)

example.net DOMAIN
me@??? example+me
you@??? example+you
she@??? example+she

Using this command as the mailbox command:
mailbox_command = /usr/bin/maildrop -d $USER $EXTENSION

This idea is from postfix, I don't know if it is aplicable on exim.

$EXTENSION can be evaluated in the users maildropfilter file. Would this maybe
work?
One problem remains: How to make a virtual table in which can only be adresses
defined for _one_ domain and place it in a users homedir.

I hope you get the picture...
Any hints appreciated!
Thanks,
Florian