disable the imsg buffers profiling code unless requested, this will prevent all
processes waking up every second
ASR field renames
do not add a user-agent
a queue user is mandatory, do not attempt _smtpd and fallback to _smtpq
more informative log message on unknown SNI.
remove old instructions about sendmail
do not call purge_task every 10 secs, it is only needed once at startup and
will cause the parent process to wake up unnecessarily at runtime