2.3.7 slower than 2.3.6?

[Ralf Hildebrandt]

We're using dovecot (via LMTP) as a backup for all incoming mail.

I upgraded from 2.3.6 to 2.3.7 on the 12th:
2019-07-12 14:35:44 upgrade dovecot-imapd:amd64 2:2.3.6-2~bionic 2:2.3.7-8~bionic

and it seems that 2.3.7 is slower than 2.3.6 -- mail to the backup
IMAP box is suddenly taking quite some time to get delivered and is piling up
in the queue.

doveconf -n:
============

default_vsz_limit = 2 G
lmtp_user_concurrency_limit = 10000
mail_attachment_dir = /home/copymail/attachments
mail_fsync = never
mail_location = mdbox:~/mdbox
mail_plugins = zlib fts
mdbox_rotate_size = 128 M
... namespaces ...
plugin {
  fts_autoindex = yes
  fts_languages = de,en
  zlib_save = gz
  zlib_save_level = 5
}
protocols = " imap lmtp"
userdb {
  args = username_format=%u /etc/dovecot/passwd
  driver = passwd-file
}
protocol lmtp {
  mail_plugins = zlib fts
}
      

-- 
Ralf Hildebrandt
  Geschäftsbereich IT | Abteilung Netzwerk
  Charité - Universitätsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | https://www.charite.de