question on Dovecot replication

[Arnold Wang]

I'm running Dovecot 2.2.x and have a question on its replication capability.
I plan to run Dovecot in two different sites with two nodes at each site. My question is how many replication partners can each Dovecot node have? Can I define three "mail_replica" entries in every node so any message received by one node will be replicated to three other nodes automatically?
Thanks in advance for your help.