Why IMAP Is Used For Storage
From Kolab Wiki
DRAFT -- This text was written by a new Kolab user. Once someone more experienced has verified its accuracy, this disclaimer can be removed.
Kolab stores many resources in IMAP e-mail folders including calendar events, To-Do items, journal entries and notes. At first it may seem strange to store all these things in IMAP folders. There are number of reasons this turns out to be useful.
IMAP is standard
E-mail users and administrators are already familiar with IMAP.
Easy network access through common protocols
Current network hardware and software settings usually permit SMTP, IMAP and HTTP connections. Using these well known protocols reduces the need of adjusting firewall or gateway settings when trying to access kolab servers.
IMAP solved key resource sharing problems
IMAP already has key features for groupware resource sharing. It has a "shareable folders" concept, and many clients exist already to sychronize one set of IMAP folders with another. This is useful for those want to sync a laptop or other mobile device to work offline.
One storage system is simple
If Kolab were to store calendars, todos, journal entries and notes each with their own kind of server, the system would only become more complex.
Kolab does not require that you use its IMAP server for e-mail
For maximum functionality, Kolab's IMAP server should be used to store the e-mail of the group members.
However, for simple contact and calendar sharing, this is not required. Each user can subscribe to shared folders for resources that they can read and write to. Changes are made and communicated in these folders by simply using IMAP and /without/ sending other e-mails.
The use of IMAP to store non e-mail resources can be transparent
Kolab and the Kontact client is setup by default to hide the use IMAP folders for other things besides e-mail. If needed, e-mail with these resources is automatically filtered when it arrives, never going to the e-mail Inbox.
KMail hides these folders unless you adjust the preferences to unhide the groupware folders (Under "Misc: Groupware"i in the settings).