fts-dovecot plugin


The Dovecot FTS driver is a part of OX Dovecot Pro only.

See also

See Dovecot Pro FTS Engine for detailed information.



New in version v2.3.5.

Upload locally cached FTS indexes to object storage every N new emails. This reduces the number of emails that have to be read after backend failure to update the FTS indexes, but at the cost of doing more writes to object storage.

The recommended value is 10. This will become the default in a future release.


New in version v2.3.15.

FTS lookups will fail and error message will be logged, when the number of triplets exceeds the threshold specified in the setting. 0 means there is no maximum number of triplets to be exceeded.

The recommended value is 200. This will become the default in a future release.

  • Default: 128 kB

  • Values: Size

New in version v2.3.5.

The smallest FTS triplet is getting recreated whenever indexing new mails until it reaches this size. Then the triplet becomes merged with the next largest triplet.

When fts-cache is used, this effectively controls how large the fts.L file can become in metacache until the FTS triplet is uploaded to object storage.

  • Default: <empty>

  • Values: String

Define the location for the fts cache and indexes path on remote filesystems.

It must be somewhat synchronized with obox_fs and mail_location.

It is strongly recommended to use fscache to speed up obox and Dovecot FTS Engine operation.

It is recommended that the FTS and email fscaches point to DIFFERENT locations.

A simple example with local storage for FTS:

mail_plugins = $mail_plugins fts fts_dovecot

plugin {
  fts = dovecot
  fts_dovecot_fs = posix:prefix=/var/fts/%u/

Example configurations for different object storage backends:


New in version v2.3.5.

Specifies how prefix search should be invoked. May not work with some filters.





Equivalent to 0-255


Search strings with that length will be treated as prefixes (e.g. 4-, 3-10)


No prefix searching is performed.


New in version v2.3.21.

Enable tracking per-folder message counts in fts.S stats file. This is useful for the “doveadm fts check fast” command to return per-folder results. Note that this changes the fts.S file format to be backwards incompatible, so this should be enabled only after all backends in the cluster have been upgraded. Old Dovecot versions won’t fail when they see the new fts.S file, but it needs to be regenerated, which can temporarily cause bad performance.