[exim] RHEL4 - Exim 4.x - cluster solution

Hi

I need to design and then build a clustered setup that is scalable that
will distribute our MTA's across 2 of our datacentres. I have 4 boxes so
there will be 2 in each location, more should be able to be added later
if required. I will be configuring this in a master/standby config
rather than balancing the load between them. I am thinking about running
a linux ha cluster on these boxes and just treating all 4 as 2 sets of 2.

I guess my questions are does exim play nicely in a linux ha type
situation and if not what other ways can be employed to maintain a ha
cluster of mta's ?

thanks