There is no native options for redundancy, you are looking
at something like DoubleTake or clustering.

One can configure two routing group connector with 
different cost. Lets say primary with 10 and secondary RGC 
with 20 and both are pointing to different bridgehead 
servers. We can then setup a rule in smart host that if 
primary bridgehead server ip not reposing, start delivering 
emails to secondary bridgehead server.

There is an option in the mailbox store of the first 
routing group in the server that contains the mail box of a 
user. Drill down till the sorage group, right click and 
select properties, in general tab, you can find "Archive 
all messages sent or received by mailboxes on this store. 
create a mail box enabled account called "master" (or 
anything you may like ;-)) and  select the account by 
browsing the accounts. so that user collects all the sent 
and received mails thrugh this store. Create a outlook 
account in a seperate machine for the user and bingo ... u 
have all the mails.