Cyrus IMAP Server: Alternate Namespace
This document describes the alternatives to the standard mailbox
presentation method. These alternatives may be used together or
independently.
The namespace options do NOT change the rules governing the behavior of
mailboxes (as described in overview.html) or how mailboxes are stored
on the filesystem. The mailboxes are ALWAYS stored using the netnews
convention and internal namespace. When configured to use one (or both)
of the options below, the server simply translates mailbox names
between the internal names and the external names when used by the
client in the IMAP protocol and in Sieve scripts.
This design allows the namespace to be changed at runtime (even on a
running server) without having to reconfigure the server. This also
means that one mailstore can support multiple namespaces if configured
correctly.
NOTE: If you are upgrading an existing server which uses timsieved to
manage Sieve scripts and choose to enable one of the namespace options,
you should run the script "tools/translatesieve" after configuring the
namespace option(s). This script will translate the folder names in
fileinto actions.
Alternate Mailbox Namespace
The alternate namespace allows a user's personal mailboxes to appear as
if they reside at the same level as that user's INBOX as opposed to
children of it. For example, if user "bovik" had a personal "work"
mailbox, it would appear to user "bovik" as "work" instead of
"INBOX.work" as it would in the standard namespace.
This configuration requires that a special prefix be used for shared
folders (to distinguish them from personal folders) and for accessing
other users' folders. By default, the prefix for shared folders is
"Shared Folders" and the prefix for other users folders is "Other
Users". For example, a shared folder "foo" in the standard namespace
would be presented as "Shared Folders.foo" in the alternate namespace.
NOTE: All tools for administering the server, including admins using
cyradm, always use the internal namespace.
Configuring the Alternate Namespace
To use the alternate namespace, turn on the altnamespace option in
/etc/imapd.conf. The prefixes used for shared folders and other users
folders can be changed from the defaults by setting the sharedrefix and
userprefix options respectively.
UNIX Hierarchy Convention
The UNIX hierarchy convention uses the traditional UNIX separator
character ("/") to delimit levels of the mailbox hierarchy instead of
the netnews character ("."). For example, if user "bovik" had a
personal "work" mailbox, it would appear to user "bovik" as
"INBOX/work" in the standard namespace.
When the UNIX hierarchy convention is used, the "." character MAY be
used in mailbox names, including user names. In order to maintain
backwards compatibility with the internal namespace, all "." characters
are translated to a benign character (currently "^") before any data is
stored to disk. For example, if user "elmer.fudd" had a personal
"rabbit.holes" mailbox, it would be stored as
"user.elmer^fud.rabbit^holes" in the internal namespace. It is
important to remember this phenomenon if/when reverting back to the
netnews hierarchy convention.
Configuring the UNIX Hierarchy Convention
To use the UNIX hierarchy separator, turn on the unixhierarchysep
option in /etc/imapd.conf.