I think you're trying to do the same as I am.
I have a local network with 8 users on it (small office environment), who share a DSL internet connection. I need for all users to have their own local email addresses so that they can forward mail to each other, however when they email to the internet, I need for them to all use the same single email address. The diagram on the OP seems to describe that.
Example:
Local addresses:
user1@local.domain,
user2@local.domain,
user3@local.domain
all route to
user1@internet.com.
I've set this up as best I can, and got sendmail to masquerade the local user address as the internet email address. However, i can't get Scalix to use sendmail to do it.
I've put the relevant sendmail command in unix.mapper, but for some reason all the emails to the internet gateway are just sitting there in the queue not going anywhere.
Any ideas as to what else I can try?
Tx,
Luke