Combining Access Rights

Access rights can combined to set a typical set of “read”, “write” and “full control”, potentially making it easier for client implementors to present their users with an interface to administer the ACLs to their mailboxes easily.

Note

RFC 4314 defines combinations of rights that should resulted in an untagged READ-ONLY or READ-WRITE response to a SELECT command, depending on whether the user has flag modification rights such as the t for maintaining \Deleted flags on messages, and the w right for maintaining non- system flags on messages.

Cyrus IMAP responds with READ-ONLY if the mailbox’s /vendor/cmu/cyrus-imapd/sharedseen annotation is set to true and the user selecting the mailbox is not given the e, i, n, t or w right.

lrs

The set of rights often referred to as “read-only”. The ACI subject is allowed to lookup the folder, read its contents and maintain \Seen flags on messages. Meanwhile, the \Recent flags are maintained for the ACI subject as well.

lirstw

The set of rights that could arguably be referred to “semi-full”.

The ACI subject is allowed to lookup the folder, read its contents and maintain flags on messages, as well as insert new messages in to the folder, and flag messages as \Deleted, but not expunge the folder’s contents.

Allowing ACI subjects to flag messages as \Deleted but not delegating the right to EXPUNGE the folder’s contents enables messages to quickly be restored by ACI subjects themselves, if the client used can be configured to show or hide messages flagged \Deleted.

Please note that the configuration value of /vendor/cmu/cyrus-imapd/sharedseen on the folder has no bearing on the \Deleted flag, but only on the \Seen flag. To be more precise, all flags other than \Seen are global.

ACL “Macros”

Cyrus adminitration supports short-hand macros you may use:

none

Remove any existing ACL for this ACI

read (lrs)

Grant the ACI read-only access to the mailbox (lookup, read and seen).

post (lrsp)

Give the ACI read access to the mailbox, and allow them to post to the mailbox using the delivery system (lookup, read, seen and post).

Most delivery systems do not provide authentication, so the p right usually has meaning only for the “anonymous” user.

append (lrsip)

The ACI can read and append to the mailbox, either through IMAP, or through the delivery system.

write (lrswipkxtecd)

The ACI may do pretty much anything with a mailbox, and folders within it.

delete (lrxte)

The ACI may list, read, delete and expunge messages and delete folders.

all (lrswipkxtecda)

Same as write, plus admin rights.

Features and Combined Access Rights

For most features, ACI subjects need certain access rights on a folder in order to perform or control the feature.

METADATA

In order to be allowed to retrieve and/or set annotations on a folder, the ACI subject requires the l right, and any one of the r, s, w, i or p rights.