IMAP is just for mail access. It isn't designed to do address books and store other preferences by itself. What your're looking for is IMSP. Quoting the abstract:
The Internet Message Support Protocol (IMSP) is designed to support the provision of mail in a medium to large scale operation. It is intended to be used as a companion to the IMAP4 protocol [IMAP4], providing services which are either outside the scope of mail access or which pertain to environments which must run more than one IMAP4 server in the same mail domain. The services that IMSP provides are extended mailbox management, configuration options, and address books.IMSP was superceeded by ACAP in the mid to late '90s. There's a Cyrusoft Guide to IMSP and ACAP that you may want to look at.
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