# Cyrus IMAP Server Release Information

IMAP (Internet Message Access Protocol) is an Internet standards-track protocol for accessing messages (mail, bboards, news, etc). The Cyrus IMAP server differs from other IMAP server implementations in that it is generally intended to be run on "sealed" servers, where normal users are not permitted to log in. The mailbox database is stored in parts of the filesystem that are private to the Cyrus IMAP system. All user access to mail is through the IMAP, POP3, or KPOP protocols.

The private mailbox database design gives the server large advantages in efficiency, scalability, and administratability. Multiple concurrent read/write connections to the same mailbox are permitted. The server supports access control lists on mailboxes and storage quotas on mailbox hierarchies.

This system should be expected to have the same order-of-magnitude installation complexity as a netnews system. Maintenance should have similar complexity, except administrators will have to deal with creation and deletion of users and will have the option of managing quotas and access control lists.

This server has been successfully installed on a number of Unix systems. The following are notes on particular Unix variants:

- HP-UX 9.0.4: Comments from testers:

  The C that ships with HP-UX is totally unsuited for use with unix packages. Either the HP-UX ANSI C developers kit must be purchased separately from HP or GNU's gcc compiler (which can bootstrap itself from the basic HP C) must be built on the target system.

  The author further notes that the memory mapping support in HP-UX is lacking on 9.0 versions of HP-UX and 10.20 as well; it appears this is related to the hardware's use of inverse page tables. It is recommended that large-scale sites consider using some other platform for IMAP servers.

The following are notes on specific Unix features:

- On any system with shadow passwords (including Solaris 2.5 with Unix authentication), read the SASL documentation carefully to make sure it is configured correctly.

Send problems/questions/suggestions to `cyrus-bugs@andrew.cmu.edu`. Be sure to include the version numbers of imapd and libsasl, the platform you are on, and what configuration options you selected.

The "`info-cyrus@andrew.cmu.edu`" mailing list exists for the discussion of this server and other Cyrus software. Send mail to "`info-cyrus-request@andrew.cmu.edu`" to subscribe.

The Cyrus server supports the IMAP4rev1 protocol described in RFC 2060, with the exception that it does not currently support the hierarchical behavior of the RENAME command. IMAP4rev1 has been approved as a proposed standard.

Character sets supported for searching are: us-ascii, iso-8859-1, iso-8859-2, iso-8859-3, iso-8859-4, iso-8859-5, iso-8859-6, iso-8859-7, iso-8859-8, iso-8859-9, koi8-r, and iso-2022-jp. The character mapping tables most likely contain errors.

The server may be compiled to support the KERBEROS_V4 authentication mechanism described in RFC 1731. The POP3 server can support MIT's KPOP protocol.

The mailbox namespace is like that for netnews--hierarchical names separated by the "`.`" character. Mailboxes without a parent may only be created by an administrator. Mailboxes with a parent may be created as the ACL (Access Control List) on the parent mailbox permits.

Users' personal mailboxes are under the "`user`" hierarchy. The names of the personal mailboxes for user "`bovik`" all start with the prefix "`user.bovik.`". The mailbox "`user.bovik`" is special in that it is presented to user "`bovik`" as if it were named "`INBOX`". Creating the mailbox "`user.bovik`" is equivalent to creating an account for user "`bovik`"--it permits "`bovik`" to receive mail, create personal mailboxes, and subscribe to mailboxes. Deleting the mailbox "`user.bovik`" has the special-case side-effect of deleting all mailboxes starting with "`user.bovik.`" and of deleting the subscriptions for "`bovik`."

If you want to install the server, be sure to read the install instructions along with the server overview.

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