There is still no real rival to Microsoft Exchange as a business mail solution, although many stand alone tools exist, they are fragmented as a toolset and fragmented in their implimentation methods.
I'd like to work on an existing tool set (from my research Mozilla Thunderbird and Sunbird appear usable) to bring together functionality to make a usable base mail and calander and contact system that could be packaged into an mail solution for use with ubuntu and other linux distributions potentially.
There are other tools, I suggest these as they exist, have a usable code base and are not tied to a desktop release.
A general outline exists as such
1.) Server Package
An imap server - this is essentially exchange's mail solution, and allows online/offline messages while leaving content on the servers giving multiple clients and web clients the same view of the current mail.
A directory for contacts, ldap seems the obvious choice for this, more so if this is an business product, which would allow desktop general auth, mail auth and provide a contact directoy
A calander service, this needs to exist in the same form as "imap" where updates are made to the server but synced to local clients. I'm not aware of a product capable of this yet, but as sunbird uses sqlite backend, this seems possible at a high level. Used along side ldap auth, this would provide a powerful feature.
2.) a Desktop Package
Deployment of a mail and calander product (thunderbird/sunbird) deployment of ldap client
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