$ cat 10-logging.conf
##
## Log destination.
##

# Log file to use for error messages. "syslog" logs to syslog,
# /dev/stderr logs to stderr.
log_path = /var/log/dovecot.log

# Log file to use for informational messages. Defaults to log_path.
info_log_path = /var/log/dovecot-info.log
# Log file to use for debug messages. Defaults to info_log_path.
debug_log_path = /var/log/dovecot-debug.log

# Syslog facility to use if you're logging to syslog. Usually if you don't
# want to use "mail", you'll use local0..local7. Also other standard
# facilities are supported.
#syslog_facility = mail

##
## Logging verbosity and debugging.
##

# Log unsuccessful authentication attempts and the reasons why they failed.
#auth_verbose = no

# In case of password mismatches, log the attempted password. Valid values are
# no, plain and sha1. sha1 can be useful for detecting brute force password
# attempts vs. user simply trying the same password over and over again.
#auth_verbose_passwords = no

# Even more verbose logging for debugging purposes. Shows for example SQL
# queries.
#auth_debug = no

# In case of password mismatches, log the passwords and used scheme so the
# problem can be debugged. Enabling this also enables auth_debug.
#auth_debug_passwords = no

# Enable mail process debugging. This can help you figure out why Dovecot
# isn't finding your mails.
#mail_debug = no

# Show protocol level SSL errors.
#verbose_ssl = no

# mail_log plugin provides more event logging for mail processes.
plugin {
  # Events to log. Also available: flag_change append
  #mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
  # Available fields: uid, box, msgid, from, subject, size, vsize, flags
  # size and vsize are available only for expunge and copy events.
  #mail_log_fields = uid box msgid size
}

##
## Log formatting.
##

# Prefix for each line written to log file. % codes are in strftime(3)
# format.
#log_timestamp = "%b %d %H:%M:%S "

# Space-separated list of elements we want to log. The elements which have
# a non-empty variable value are joined together to form a comma-separated
# string.
#login_log_format_elements = user=<%u> method=%m rip=%r lip=%l mpid=%e %c

# Login log format. %$ contains login_log_format_elements string, %s contains
# the data we want to log.
#login_log_format = %$: %s

# Log prefix for mail processes. See doc/wiki/Variables.txt for list of
# possible variables you can use.
#mail_log_prefix = "%s(%u): "

# Format to use for logging mail deliveries. You can use variables:
#  %$ - Delivery status message (e.g. "saved to INBOX")
#  %m - Message-ID
#  %s - Subject
#  %f - From address
#  %p - Physical size
#  %w - Virtual size
#deliver_log_format = msgid=%m: %$