Peter:
> guess it is something beyond postfix to handle. not sure how postfix
> users will handle such an issue?
You are looking for a two-way replicated message store. Postfix is
an MTA. Postfix is not a storage manager.
Two-way storage replication is a commodity solution if the systems
are connected by a high-speed interconnect (examples of this are
RAID in hardware or software).
Two-way storage replication becomes non-trivial if the systems are
connected by a wide-area network. That is a specialized niche that
few Postfix users will have experience with (I certainly don't).
For example you get massive file system corruption when you simply
mount an ext4fs-over-drbd file system on two active hosts. Instead,
you need to use a file system that is explicitly built for concurrent
updates by different hosts (GFS, OCFS and the like).
Even a replicated distributed file system will get into trouble
when the two sites become isolated from each other, but they keep
receiving mail. Those file system updates are likely to conflict
with each other.
Wietse
