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       maildiracl - manage access control lists


       maildiracl {-reset} {maildir}

       maildiracl {-list} {maildir} {INBOX[.folder]}

       maildiracl {-set} {maildir} {INBOX[.folder]} {[-]identifier}

       maildiracl {-delete} {maildir} {INBOX[.folder]} {[-]identifier}

       maildiracl {-compute} {maildir} {INBOX[.folder]} {identifier...}


       maildiracl manages “access control lists” (or ACLs) of the Courier IMAP
       server maildir folders. Access control lists are used primarily to
       provide fine-grained control for accessing virtual shared folders via

           The Courier IMAP server server implements two types of shared
           folders: filesystem permission-based shared folders, as well as
           virtual shared folders based on IMAP access control lists. Use the
           maildiracl command to set up access control lists for virtual
           shared folders. Use the maildirmake(1)[1], command to implement
           shared folders based on filesystem permissions.

           See the Courier IMAP server documentation for additional
           information on setting up virtual shared folders.

   ACL overview
       ACLs provide a fine-grained mechanism for controlling access to shared
       folders. ACLs may be used to specify, for example, that user1 may only
       open and read the messages in the folder; and user2 can not only do
       that, but also delete messages, and create subfolders.

       Each folder maintains its own individual access control list, that
       specifies who can do what to the folder. An ACL is a list of
       “identifier” and “rights” pairs. Each “identifier” and “rights” pair
       means that an entity called “identifier” (using the UTF-8 character
       set) is allowed to do “rights” on this folder.  “rights” consists of
       one or more letters, each letter signifies a particular action:


           identifier may modify this folder´s ACLs.


           identifier may create subfolders of this folder (this includes
           renaming another folder as this folder´s subfolders).


           identifier may remove deleted messages from this folder.


           identifier may add messages to this folder (either uploading them
           one by one, or copying messages from another folder).


           identifier may actually see that this folder exists. If identifier
           does not have the “l” right on this folder, the folder is
           effectively invisible to identifier.


           identifier may open this folder. Note that if identifier knows the
           name of this folder, it can open it even if identifier does not the
           “l” right on this folder.


           identifier may mark messages in this folder as seen, or unseen.


           identifier may mark messages in this folder as deleted, or


           identifier may change other status flags of messages in this
           folder. May also add or remove custom keywords on individual


           identifier may delete this folder (which includes renaming this
           folder as another mailbox´s subfoler.

       Negative rights
           An ACL entry of “-identifier” and “rights” is called a “negative
           right”, which explicitly removes “rights” from “identifier”. More
           than one “identifier” is usually used to determine the actual
           rights someone has for the given folder. The actual access rights
           are determined by taking all rights from all applicable identifier,
           than subtracting any negative rights, as specified in the following

           Access rights on a given folder are computed by obtained the rights
           on the following identifiers, then subtracting the negative rights
           on the same identifiers:

               The owner of the maildir containing this folder. The maildir´s
               INBOX´s ACL defaults to all rights for its owner. A new
               folder´s ACL is the same as its parent´s ACL. In all cases,
               trying to remove the “a” right from the owner (either directly
               or using a negative right) results in an error.

               This identifier refers literally to every userid. The
               associated rights (or negative rights) are always used.

               This is a synonym from “anyone”.

               Rights (or negative rights) for IMAP account “loginid”.

                   “loginid” is what´s logged to syslog after a succesful
                   login. In some situations “loginid” is not exactly the
                   actual login ID used by the IMAP client.

               Rights (or negative rights) for account group “name”. Access
               rights are granted to an account group as a whole. The account
               options feature of the Courier Authentication Library specifies
               which account belongs to which account group. See
               courier-authlib´s documentation for more information.

               This is an alias for “group=administrators”. Accounts that are
               members of an account group called “administrators” are
               considered administrative accounts, and automatically receive
               all access rights on all accessible folders.

           Consider the following access control list:

               owner          aceilrstwx
               anyone         lr
               user=john      w
               -user=mary     r
               administrators aceilrstwx

           This access control list specifies that the folder´s owner has
           complete control over the mailbox (as well as the administrators,
           which have complete access to every folder); everyone else can see
           it and open it, except for “mary” who can see that the mailbox
           exists, but can´t open it; additionally, “john” can change the
           status and keywords of individual messages (but not mark them as
           deleted/undeleted or seen/unseen, which requires additional


       maildiracl -reset maildir

       This command resets access control lists in maildir which as a path to
       a maildir. Under certain conditions, the files where a folder´s ACLs
       are saved may continue to exist after the folder is removed. The -reset
       options goes through maildir and removes all stale ACL files for
       removed folders.

           The Courier IMAP server normally performs this maintenance function
           automatically. It is not necessary to run this command under normal

       maildiracl -list maildir folder

       This command lists the access control lists set for folder.  folder
       must be either “INBOX” or “INBOX.folder.subfolder”, which is the same
       naming convention for the Courier IMAP server.

       maildiracl -set maildir folder identifier rights

       Puts identifier (which may begin with a minus sign to specify a
       negative right) and rights in folder´s access control list. Existing
       rights for identifier (or identifier) are replaced by rights unless
       “rights” begins with “+” or “-”, which modifies the existing rights by
       adding or removing from them accordingly. Some examples:

           maildiracl -set /home/user1/Maildir INBOX.Sent user=john lr

           maildiracl -set /home/user2/Maildir INBOX.Notes anyone -r

           maildiracl -set /home/user3/Maildir INBOX.Private -user=tom +r

           Observe that the last command revokes the “r” right from “tom”, by
           adding it as a negative right.

       maildiracl -delete maildir folder identifier

       This command removes identifier from folder´s access control list, if
       it exists. Use “-identifier” to remove negative rights.

       maildiracl -compute maildir folder [identifier]+

       This command takes a list of one or more identifiers. All access rights
       for the identifiers are combined together, then any appropriate
       negative rights are removed, and the result is printed on standard
       output. Use the following procedure to compute access rights the same
       way as they are computed by the Courier IMAP server:

           maildiracl -compute /home/tom46/Maildir INBOX.Sent owner user=tom46

       This command computes access rights “tom46” has on his own folder.

           maildiracl -compute /home/john34/Maildir INBOX.Public user=tom46

       This command computes access rights “tom46” has on “john34”´s folder.


       The owner of the mailbox must always have the “a” amd “l” access
       rights. The administrators group must always have all access rights to
       all folders. Attempts to set access control lists, that do not include
       these minimum access rights, will be rejected.


       All identifiers are specified using the UTF-8 character set.

       All non-Latin letters in folder names are specified using the
       modified-UTF7 coding as used in IMAP.

       This implementation of access control lists is based on version 2 (or
       “ACL2”) of IMAP access control lists, which is a work-in-progress. The
       existing IMAP ACL, RFC 2086[2] is transparently implemented inside the
       ACL2 model.

       If history´s of any guidance, ACL2 is subject to change at any time. Be
       sure to check the release notes when upgrading to a newer version of
       this software. The “ACL overview” portion of this manual page is a very
       brief summary of ACL2, which leaves out optional parts of ACL2 that are
       not implemented.


       maildirmake(1)[1], maildirkw(1)[3],


        1. maildirmake(1)
           [set $man.base.url.for.relative.links]/maildirmake.html

        2. RFC 2086

        3. maildirkw(1)
           [set $man.base.url.for.relative.links]/maildirkw.html