zlib plugin

See also

See Zlib plugin for a plugin overview.

Settings

zlib_save

• Default: <empty>

• Values: String

The compression algorithm to use. This setting is REQUIRED - if empty, the plugin is disabled.

The following algorithms are supported:

Name	Library (algorithm)	Dovecot Support
bz2	libbzip2 (bzip2)	v2.0+
gz	zlib (gzip)	v2.0+
lz4	liblz4	v2.2.11+
xz	liblzma	DEPRECATED (v2.2.9+ reading, v2.2.9-v2.3.13 writing)
zstd	Zstandard	v2.3.12+

Example:

zlib_save = gz

zlib_save_level

• Default: <algorithm dependent>

• Values: Unsigned integer

The compression level to use. This value is dependent on the algorithm chosen in zlib_save.

The following levels are supported:

Name	Minimum	Default	Maximum
bz2	1	9	9
gz	0 (no compression)	6	9
lz4	1	1	9
zstd	1	3	22

Example:

zlib_save_level = 6

Changed in version v2.3.15: Prior to v2.3.15, the compression level must be an integer in the range 1 to 9 regardless of the algorithm selected. The default level is 6. This value may not make sense with compression algorithms other than gz and bz2. For example, zstd supports levels from 1 to 22 in latest versions.