fts: change autoindex to occur on mailboxes of receiving 20 or more mails daily

data/conf/dovecot/conf.d/fts.conf

@@ -3,6 +3,8 @@ plugin {
     fts_autoindex = yes
     fts_autoindex_exclude = \Junk
     fts_autoindex_exclude2 = \Trash
+    # Tweak this setting if you only want to ensure big and frequent folders are indexed, not all.
+    fts_autoindex_max_recent_msgs = 20
     fts = flatcurve
 
     # Maximum term length can be set via the 'maxlen' argument (maxlen is
@@ -26,7 +28,7 @@ plugin {
 
 service indexer-worker {
   # Max amount of simultaniously running indexer jobs.
-  process_limit=5
+  process_limit=1
 
   # Max amount of RAM used by EACH indexer process.
   vsz_limit=128 MB