Compression (fs-compress) Plugin

fs-compress plugin is used to wrap other data streams in a compression layer.

It can be used by any of the settings using the FS drivers.

The exact location where to set it in the FS driver string depends on what other FS drivers are being used.

The important rules are:

Must be set before the final storage driver (s3, sproxyd, ...)
Should be set after fscache (you generally don't want fscache to be compressed for performance reasons).
Must be set before fs-crypt, because encrypted data compresses poorly.

Settings

There are no dovecot.conf settings for this plugin.

The fs-compress configuration format is:

compress:<compress_save>:<compress_save_level>

See mail_compress_save for information on available compression algorithms.

See mail_compress_save_level` for information on compression levels and defaults.

By default, fs-compress requires that the mail is compressed with the specified algorithm.

To allow adding compression to existing storages without compression, you can use the maybe- prefix in front of the algorithm.

Example:

compress:maybe-gz:6