Switch file storage to Database engine to increase performance.
Migrate Kerio Connect from file storage to some SQL database.
This concept will allow split Kerio into modules:
1. Front-end with webmail and smtp
2. Multiple SMTP relay for load balancing
2. Back-end with Database or cluster for load balancing.
It's a good option nowadays in 21st century having mailserver protected from death and very fast database cluster for load balancing.
That's what Kerio needs.