[exim] Exim Mirror or Backup Solution

Hello Everyone:

We have the current setup running perfectly:

Exim 4.52 on RHEL 2.4.21-4.0.1 (this is a cpanel box, not sure if
this makes a difference with my question). There is also a POP3 and
IMAP server running on this box.

This computer is located in a data center in US and in addition to
Exim, runs various other services. Our main offices are Kuwait. I
would like to setup Exim on one of our local servers here such that :

1. The local Exim server holds backup of all emails sent/recieved
from the "main" server.
2. Local delivery takes places without a trip to the US over the
Internet. Internet is not very reliable in Kuwait (also is very
expensive).

90% of my users are in our local office, but I do have a few road
warriors (10) and have an average of 5 to 7 users in the field sending
and recieving messages. Can someone please point me in the right
direction to setup a solution that solves this problem? I searched
myself, but I'm not sure if the fetchmail-to-IMAP-store solution will
help me here. Mainly I'm concerned about the remote users (these
people travel alot). I do not want to have a large delay between the
time they send a message till the time that fetchmail kicks in and
messages are available to the local users. Also, I'm concerned with
having to make redundant trips or fall into a loop where messages are
being sent to the US server, fetched, then sent again (read about this
in a recent thread).

Any guidance along these lines would be much appreciated.

Warmly,
Burhan