add optional Maildir-Compression

core/dovecot/conf/dovecot.conf

@@ -32,7 +32,7 @@ mail_access_groups = mail
 maildir_stat_dirs = yes
 mailbox_list_index = yes
 mail_vsize_bg_after_count = 100
-mail_plugins = $mail_plugins quota quota_clone
+mail_plugins = $mail_plugins quota quota_clone zlib
 
 namespace inbox {
   inbox = yes
@@ -58,6 +58,14 @@ plugin {
   quota = count:User quota
   quota_vsizes = yes
   quota_clone_dict = redis:host={{ REDIS_ADDRESS }}:port=6379:db=1
+
+  {% if COMPRESSION in [ 'gz', 'bz2' ] %}
+  zlib_save = {{ COMPRESSION }}
+  {% endif %}
+
+  {% if COMPRESSION_LEVEL %}
+  zlib_save_level = {{ COMPRESSION_LEVEL }}
+  {% endif %}
 }
 
 ###############

docs/compose/.env

@@ -87,6 +87,12 @@ WELCOME=false
 WELCOME_SUBJECT=Welcome to your new email account
 WELCOME_BODY=Welcome to your new email account, if you can read this, then it is configured properly!
 
+# Maildir Compression
+# choose compression-method, default: none (value: bz2, gz)
+COMPRESSION=
+# change compression-level, default: 6 (value: 1-9)
+COMPRESSION_LEVEL=
+
 ###################################
 # Web settings
 ###################################