[Exim] Redirecting outgoing emails from one user for moderat…

I am the admin for a medium sized business and have been asked to set up a
moderation system for a certain user.

All emails the user sends are not to be delivered and should instead go to a
local mailbox. From there the moderator can check the emails and then send
them out under the users name so that nothing appears to be different. We are
trying to keep the user from knowing this moderation is taking place, they are
not that computer literate so extra bits in the email headers do not matter.

Is this at all possible? The server is Debian Linux running Exim 4.22.

Andreas Koepke