This documentation is for Dovecot v2.x, see wiki1 for v1.x documentation.

Lazy expunge

The idea behind this plugin is that expunged mails and deleted mailboxes stay around for a while, so that user can undelete them without assistance from sysadmin. The expunged mails won't be counted in user's quota. The plugin itself doesn't clean up the expunged messages, you'll have to do it some other way (see below).

The plugin is configured by defining namespaces where the mails are moved. You can decide if you want the namespaces to be visible to clients, or if you want to show them only via some special webmail interface.

1 mailbox (v2.2.24+)

You create a single mailbox. All messages that are expunged from all the mailboxes are moved there. This is the simplest configuration. The mailbox is created automatically. You probably also want to hide it with an ACL.

mail_plugins = $mail_plugins lazy_expunge acl
plugin {
  lazy_expunge = .EXPUNGED
  acl = vfile:/etc/dovecot/dovecot.acl

  # Expunged messages most likely don't want to be included in quota:
  quota_rule2 = .EXPUNGED:ignore
}

Where /etc/dovecot/dovecot.acl contains:

.EXPUNGED owner rwstipekxa

You could also leave the permissions empty if you don't want to allow clients to access it at all.

1 namespace

You create only a single namespace. When a message is expunged from mailbox <name>, it's moved to a mailbox <name> in the expunge namespace. When an entire mailbox <name> is deleted, it's also moved to this namespace as <name>. If it already exists, their contents are merged.

Example configuration:

# the default namespace
namespace {
  prefix =
  separator = /
  inbox = yes
}

# namespace for lazy_expunge plugin:
namespace {
  prefix = .EXPUNGED/
  hidden = yes
  list = no
  separator = /
  location = maildir:~/Maildir/expunged
}

mail_plugins = $mail_plugins lazy_expunge
plugin {
  lazy_expunge = .EXPUNGED/
}

3 namespaces (obsolete, v2.0 only)

The namespaces are:

  1. Expunged messages namespace. Whenever a message is expunged in mailbox <name>, it's moved to a mailbox <name> in this namespace. The mailboxes are created automatically as needed.

  2. Deleted mailboxes namespace. Whenever a mailbox <name> is deleted, it's moved here with name <name>-YYYMMDD-hhmmss. The timestamp is there so that the mailbox can be deleted multiple times. If the mailbox is deleted multiple times within a second, random 16bit hex value is appended to it.

  3. Expunged messages in a deleted mailbox namespace. When a mailbox is deleted and it has messages in its expunged namespace, the mailbox is moved from the expunged namespace to this namespace. The destination mailbox name is the same as in the 2nd namespace (ie. contains the same timestamp).

Example configuration:

# the default namespace
namespace {
  prefix =
  separator = /
  inbox = yes
}

# namespaces for lazy_expunge plugin:
namespace {
  prefix = .EXPUNGED/
  separator = /
  location = maildir:~/Maildir/expunged
}
namespace {
  prefix = .DELETED/
  separator = /
  location = maildir:~/Maildir/deleted
}
namespace {
  prefix = .DELETED/.EXPUNGED/
  separator = /
  location = maildir:~/Maildir/deleted/expunged
}

mail_plugins = $mail_plugins lazy_expunge
plugin {
  lazy_expunge = .EXPUNGED/ .DELETED/ .DELETED/.EXPUNGED/
}

Multi-dbox

With multi-dbox use different MAILBOXDIRs (so copying between namespaces works quickly within the same storage), but otherwise exactly the same paths (index, control):

# the default namespace
namespace {
  prefix =
  inbox = yes
  location = mdbox:~/mdbox:INDEX=/var/index/%d/%n
}

# lazy_expunge namespace(s):
namespace {
  prefix = .EXPUNGED/
  hidden = yes
  list = no
  subscriptions = no

  location = mdbox:~/mdbox:INDEX=/var/index/%d/%n:MAILBOXDIR=expunged
  # If mailbox_list_index=yes is enabled, it needs a separate index file (v2.2.28+):
  #location = mdbox:~/mdbox:INDEX=/var/index/%d/%n:MAILBOXDIR=expunged:LISTINDEX=expunged.list.index
}

Copy only the last instance (v2.2+)

If mail has multiple copies (via IMAP COPY), each copy is normally moved to lazy expunge namespace when it's expunged. With v2.2+ you can set plugin { lazy_expunge_only_last_instance = yes }  to copy only the last instance and immediately expunge the others. This may be useful if you want to provide a flat list of all expunged mails without duplicates in your webmail. With many clients this means that the last instance is always in the Trash mailbox.

Cleaning up

doveadm

doveadm expunge mailbox 'deleted/*' savedsince 1d

cronjob

Run something like this for each user every night (not actually tested if it works, and vulnerable to TOCTTOU if the user can place symlinks in any of the directories find is traversing):

# delete a day old mails
find Maildir/expunged Maildir/deleted Maildir/deleted/expunged \
  -type f ! -cmin 1440 -print0 | xargs -0 rm

Trash plugin

Trash plugin with some help from Quota plugin could probably be used to keep the expunged and deleted mailboxes under a specified size (not tested).

Expire plugin

Expire plugin was created to keep track of mails in specific mailboxes, and expunge them when they've been there for a specified amount of time. It keeps an internal database (e.g. SQL) of all such mailboxes, so it doesn't have to go through all the mailboxes for all the users.

None: Plugins/Lazyexpunge (last edited 2017-03-16 00:07:43 by TimoSirainen)