[Dovecot] Adding support for a new storage format - plugin?

[Brad Hards]

Hi,

I've spent a little bit of time looking at the dovecot source (from the 
unstable 2.0 development tree), and I think I'm starting to get it together...

Background:
I'm interested in dovecot to provide IMAP access to an existing database 
backed server store (http://www.openchange.org for more details). The goal is 
to provide parallel access using either IMAP or the exchange RPC protocol.

If I understand this stuff:
* I can potentially provide access to the store using a plugin. It looks like 
the virtual mailbox plugin is a potential example here.
* I may need to also provide an authentication plugin (not sure whether I can 
just re-use the existing ldap backend - quite possibly a useful option in my 
scenario)
* I probably can't use the existing SQL code, since it uses its own schema.
* I may need to provide some locking to ensure things are always in a 
consistent state for both IMAP and exchange RPC.

Comments? Suggestions? 

Brad