Redis sentinel ( http://redis.io/topics/sentinel ) is a service that monitors and manages redis master slave replication.

Using sentinel you can easily create a redis ha cluster. You can connect to a sentiniel and subscribe to certain events then in case of an failover update the redis address to new master etc.

I think this is better suited to be used with dict proxy. Do You think it can be implemented without changes to dovecot core ?

-- Michal Grzedzicki