[exim] Custom user aliases

Hi Everyone

I've finally gotten around to setting up exim4 on Ubuntu machine and
everything is working nicely.

In the fight against spam I'd like to try to setup a configuration where
local users (who have addresses like tom@???) can setup their own
custom aliases like tom-*@??? (where * is any string) and still
have mail delivered to them. This way, when "signing up" to your typical web
site you could specify that your email address is
tom-eximwebpage@??? (if you were signing up to the exim web page)
so you'd know in future when you start getting spammed which web site leaked
your details, and then you could setup a rule (using procmail maybe) to
forward to /dev/null for that particular address.

Even maybe everything delivered to tom-*@??? should be delivered to
user tom@???, and then procmail to filter. I tried putting "tom-*:
tom" into my aliases file, but getting bounces when mailing to
tom-anything@??? so clearly not working.

Any suggestions?

Thanks,
Tom