Supervisor of department has to see messages sent and received by
workers (Mr Dubiel, Mr Smith) of that department.
So I make a file /etc/exim4/copies that looks like this:
smith: supervisor
dubiel: supervisor
This file explains, that mails sent and received by Mr Smith should be
seen by supervisor and mails send and received by Mr Dubiel should be
seen by supervisor too.
In order to send mail every user has to give his name and password, so
variable $authenticated_id is set for every mail.
To do the task of copying I define two routers:
-- first one redirects a copy of mail to supervisor if $authenticated_id
is "smith" or "dubiel"
-- second one redirects mail to supervisor if target of mail
($local_part) is "smith" or "dubiel"