Paul,
I guess you could set-up a local agent on each users database.
Are you running R5? if so take a look under the Help for agents, they are quite nifty little things.
However it would still rely on the second user checking for new mail, beforeopening the note.
Could you not set-up a user as per the same name as the group then delete the group, users would e-mail the new user name, arther than the group. Add the new in-box/database to each readers workspace and instruct them, to keep actioning the messages, setting a weekly rota with an escalation period of say 2hours, before the other reader actions the note, should the designated reader be away or off?
Just an idea
Allen