First you must activate GroupMail Forwarding feature
1- Go to setting page
2- Check the box Offer GroupMail Forwarding
3- Go the a user account page
4- Enable GroupMail Forwarding Service
Forward Mail in a group
5- On the Mail list (InMail admin) page click GroupMail Forwarding button
7. Click Create new Forwarding group button
8. Find and select a subscriber
9. Check from the mail items to included in this group
10. Click Proceed to forward group
11. Forward and ship