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diff --git a/doc/wiki/MailLocation.mbox.txt b/doc/wiki/MailLocation.mbox.txt new file mode 100644 index 0000000..98d6f73 --- /dev/null +++ b/doc/wiki/MailLocation.mbox.txt @@ -0,0 +1,194 @@ +mbox configuration +================== + +See <MailboxFormat.mbox.txt> for a complete description of how Dovecot has +implemented mbox support. + +Mail location +------------- + +In many systems the user's mails are by default stored in '/var/mail/username' +file. This file is called INBOX in IMAP world. Since IMAP supports multiple +mailboxes, you'll need to have a directory for them as well. Usually '~/mail' +is a good choice for this. For installation such as this, the mail location is +specified with: + +---%<------------------------------------------------------------------------- +# %u is replaced with the username that logs in +mail_location = mbox:~/mail:INBOX=/var/mail/%u +---%<------------------------------------------------------------------------- + +It's in no way a requirement to have the INBOX in '/var/mail/' directory. In +fact this often just brings problems because Dovecot might not be able to write +dotlock files to the directory (see below). You can avoid this completely by +just keeping everything in '~/mail/': + +---%<------------------------------------------------------------------------- +# INBOX exists in ~/mail/inbox +mail_location = mbox:~/mail +---%<------------------------------------------------------------------------- + +Index files +----------- + +See <MailLocation#indexfiles> [MailLocation.txt] for full explanation of how to +change the index path. For example: + +---%<------------------------------------------------------------------------- +mail_location = mbox:~/mail:INBOX=/var/mail/%u:INDEX=/var/indexes/%u +---%<------------------------------------------------------------------------- + +Locking +------- + +Make sure that all software accessing the mboxes are using the same locking +methods in the same order. The order is important to prevent deadlocking. From +Dovecot's side you can change these from 'mbox_read_locks' and +'mbox_write_locks' settings. See <MboxLocking.txt> for more information. + +/var/mail/ dotlocks +------------------- + +Often mbox write locks include dotlock, which means that Dovecot needs to +create a new "<mbox>.lock" file to the directory where the mbox file exists. If +your INBOXes are in '/var/mail/' directory you may have to give Dovecot write +access to the directory. There are two ways the '/var/mail/' directory's +permissions have traditionally been set up: + + * World-writable with sticky bit set, allowing anyone to create new files but + not overwrite or delete existing files owned by someone else (ie. same as + /tmp). You can do this with 'chmod a+rwxt /var/mail' + * Directory owned by a mail group and the directory set to group-writable + (mode=0770, group=mail) + +You can give Dovecot access to mail group by setting: + +---%<------------------------------------------------------------------------- +mail_privileged_group = mail +---%<------------------------------------------------------------------------- + +NOTE: With <LDA.txt> the 'mail_privileged_group' setting unfortunately doesn't +work, so you'll have to use the sticky bit, disable dotlocking completely or +use LMTP server instead. + +/var/mail/* permissions +----------------------- + +In some systems the '/var/mail/$USER' files have 0660 mode permissions. This +causes Dovecot to try to preserve the file's group, and if it doesn't have +permissions to do so, it'll fail with an error: + +---%<------------------------------------------------------------------------- +imap(user): Error: chown(/home/user/mail/.imap/INBOX, -1, 12(mail)) failed: +Operation not permitted (egid=1000(user), group based on /var/mail/user) +---%<------------------------------------------------------------------------- + +There is rarely any real need for the files to have 0660 mode, so the best +solution for this problem is to just change the mode to 0600: + +---%<------------------------------------------------------------------------- +chmod 0600 /var/mail/* +---%<------------------------------------------------------------------------- + +Optimizations +------------- + +The settings below are related to mbox performance. See +<MailboxFormat.mbox.txt> for more complete description of what they do. + + * 'mbox_lazy_writes=yes' (default): Metadata updates, such as writing X-UID + headers or flag changes, aren't written to mbox file until the mailbox is + closed or CHECK or EXPUNGE IMAP commands are sent by the client. The mbox + rewrites can be costly, so this may avoid a lot of disk writes. + * 'mbox_dirty_syncs=yes' (default): Dovecot assumes that external mbox file + changes only mean that new messages were appended to it. Without this + setting Dovecot re-reads the whole mbox file whenever it changes. There are + various safeguards in place to make this setting safe even when other + changes than appends were done to the mbox. The only downside to this + setting is that external message flag modifications may not be visible + immediately. + * 'mbox_very_dirty_syncs=yes' (not default): When opening mbox file that has + been changed externally, don't re-read it. Otherwise similar to + 'mbox_dirty_syncs=yes'. + * 'mbox_min_index_size=n': If mbox file is smaller than n kilobytes, don't + update its index files. If an index file exists for it, it's still read + however. + +Only /var/mail/ mboxes +---------------------- + +With POP3 it's been traditional that users have their mails only in the +'/var/mail/' directory. IMAP however supports having multiple mailboxes, so +each user has to have a private directory where the mailboxes are stored. +Dovecot also needs a directory for its index files unless you disable them +completely. + +If you *really* want to use Dovecot as a plain POP3 server without index files, +you can work around the problem of not having the per-user directory: + + * Set users' home directory in userdb to some empty non-writable directory, + for example '/var/empty' + * Modify 'mail_location' setting so that the mail root directory is also the + empty directory and append ':INDEX=MEMORY' to it. For example: + 'mail_location = mbox:/var/empty:INBOX=/var/mail/%u:INDEX=MEMORY' + * Note that if you have IMAP users, they'll see the '/var/empty' as the + directory containing other mailboxes than INBOX. If the directory is + writable, all the users will have their mailboxes shared. + +Directory layout +---------------- + +By default Dovecot uses filesystem layout under mbox. This means that mail is +stored in mbox files under hierarchical directories, for example: + + * '~/mail/inbox' - mbox file containing mail for INBOX + * '~/mail/foo' - mbox file containing mail for mailbox "foo" + * '~/mail/bar/baz' - mbox file containing mail for mailbox "bar/baz" + +One upshot of this is that it is not normally possible to have mailboxes which +are subfolders of mailboxes containing messages. + +As an alternative, it is possible to configure Dovecot to store all mailboxes +in a single directory with hierarchical levels separated by a dot. This can be +configured by adding ':LAYOUT=maildir++' to the mail location. There are, +however, some further considerations when doing this; see +<MboxChildFolders.txt> for some examples. + +Control files +------------- + +Under mbox format, Dovecot maintains the subscribed mailboxes list in a file +'.subscriptions' which by default is stored in the mail location root. So in +the example configuration this would be at '~/mail/.subscriptions'. + +If you want to put this somewhere else, you can change the directory in which +the '.subscriptions' file is kept by using the 'CONTROL' parameter. So for +example, if we configured the mail location using: + +---%<------------------------------------------------------------------------- +mail_location = mbox:~/mail:CONTROL=~/mail-control +---%<------------------------------------------------------------------------- + +then the subscribed mailboxes list would be maintained at +'~/mail-control/.subscriptions'. + +One practical application of the 'CONTROL' parameter is described at +<MboxChildFolders.txt>. + +Message file name +----------------- + +By default, Dovecot stores messages for INBOX in an mbox file called "inbox", +and messages for all other mailboxes in an mbox file whose relative path is +equivalent to the name of the mailbox. Under this scheme, it is not possible to +have mailboxes which contain both messages and child mailboxes. + +However, the behaviour (for mailboxes other than INBOX) can be changed using +the 'DIRNAME' parameter. If the 'DIRNAME' parameter is specified with a +particular value, then Dovecot will store messages in a file with a name of +that value, in a directory with a name equivalent to the mailbox name. + +There are, however, some further considerations when doing this; see +<MboxChildFolders.txt> for an example. + +(This file was created from the wiki on 2019-06-19 12:42) |