outgoing filter on a group

hi,

someone ask me to have an outgoing filter based on a group of contact in order to sort her messages.

We have managed to do someting like this :

1. create a new contact list
2. create an outgoing filter rule
2.1. recipient = group name of contacts
2.2. move to a specified folder
...etc...

this doesn't works as we don't know how to do point 2.1.

as a workaround, we could add each user of the group to the filter rule, but each time you add a new email address to the contact group, you should remember to add it to the filter

I hope that you will understand what I want to say

Regards
Mathieu