This setting specifies the fields for mail processes’ event logging. The fields are given in a space-separated list. The following fields are available: uid, box, msgid, from, subject, size, vsize, and flags. size and vsize are available only for expunge and copy events.
mail_log_fields = uid box msgid size
This setting adjusts log verbosity, providing additional logging for mail processes at plug-in level. The setting takes a space-separated list of events to log. In addition to the events shown in the example below, flag_change and append are available.
mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
If enabled, everything except save event will log only the fields that can be looked up from cache. This improves performance if some of the fields aren’t cached and it’s not a strict requirement to log them.