Delayed Delete
**************

It is not uncommon for a folder or hierarchy of folders in IMAP to
contain large amounts of information -- after all, IMAP preserves a
copy of the messages on the server unless it is specifically deleted.

Three challenges arise when users delete folders especially if an
organization is required to comply with archiving regulations;

1. How to restore the folder if the deletion was accidental?

2. How to ensure the folder being deleted remains available for
   inclusion in the next backup cycle?

3. The deletion of a hierarchy with a lot of messages can create an
   I/O storm unlinking many individual files and some directories.

Cyrus IMAP introduces *delayed deletion* of folders, which leaves the
deleted folder (or hierarchy thereof) on the filesystem, such that
purging the folder hierarchy from the filesystem;

* becomes a separate event (perhaps triggered during the weekend),

* can be delayed such that users have a chance to report accidental
  deletion and administrators can recover without requiring a restore
  from backup,

* can be delayed as to ensure that the next backup cycle includes the
  deleted folder hierarchy.


Configuring Cyrus IMAP for Delayed Delete
=========================================

To enable or disable Delayed Delete, please check the following
settings in imapd.conf(5).

      "delete_mode:" delayed

         The manner in which mailboxes are deleted. In the default
         *delayed* mode, mailboxes that are being deleted are renamed
         to a special mailbox hierarchy under the **deletedprefix**,
         to be removed later by **cyr_expire(8)**.

         In *immediate* mode, the mailbox is removed from the
         filesystem immediately.

         Allowed values: *immediate*, *delayed*

      "deletedprefix:" DELETED

         With **delete_mode** set to *delayed*, the **deletedprefix**
         setting defines the prefix for the hierarchy of deleted
         mailboxes.

         The hierarchy delimiter will be automatically appended.

See also:

  * Delayed Expunge

  * When is What ... Deleted, Expired, Expunged or Purged?

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