[Exim] Confusing myself with expansions

I am wanting to add a facility to write all outgoing mail for some local users
in their ~/Maildir/.Sent folder

I have as my first router something like this (syntax wrong - that is what I
want help with) +local_domains is a domain list that my local users may be
using, and CONFDIR/local-users is a list of local parts for which this is
true. no_verify and unseen are meant to avoid problems with sender_verify
checks in the acl, and to make this a copy of the message.

I know the condition statements are not right, but I can't seem to find
anything in the documentation that tells me how to create a condition that
checks $sender_address_domain against my +local_domains domain list.

savemail:
driver = accept
condition = lookup {$sender_address_domain} +local_domains
condition = lookup {$sender_address_local_part} lsearch
{CONFDIR/local-users}
no_verify
unseen
transport = save_mail
user = ${lc:$sender_address_local_part}



--
Alan Chandler
alan@???