[Dovecot] Re-enable lz4 until 2.3.2 to verify replication fix

data/conf/dovecot/dovecot.conf

@@ -285,8 +285,8 @@ plugin {
   #mail_crypt_global_private_key = </mail_crypt/ecprivkey.pem
   #mail_crypt_global_public_key = </mail_crypt/ecpubkey.pem
   #mail_crypt_save_version = 2
-  # Enable compression while saving
-  zlib_save = gz
+  # Enable compression while saving, lz4 Dovecot v2.2.11+
+  zlib_save = lz4
 }
 dict {
   sqlquota = mysql:/usr/local/etc/dovecot/sql/dovecot-dict-sql-quota.conf