dovecot HA setup across large geographic distances

[Sophie Loewenthal]

Hi,

I have a working postfix/dovecot config on Debian located in Europe[EU].  I would like to provide either an HA/load balanced setup with a second site in Australia[AU] because of users located between EU/Asia/AU. The site to site traffic would be tunneled through either SSH or a VPN

* Has this been done with Doevcot over such great distances? 

* How can the delay between mailstore synchonisation be handled?  ( Currently looking for an opensource product like Netex's HyperIP)

I'd be grateful for your thoughts.

Best wishes, Sophie
Sent from a phone, thus brief.