This is the name of the "facility" used by syslogd to log MailScanner's messages. If this doesn't mean anything to you, then either leave it alone or else read the "syslogd" man page.
If this option is set, then every attachment filename that passes the "filename rules" checks will be logged to syslog. Normally this is of no interest. But if you are having trouble getting your filename rules correct, setting, this can provide useful debugging output.
This can also be the filename of a ruleset.
Log Permitted Filetypes
Log all the filenames that are allowed by the Filetype Rules, or just
the filetypes that are denied?
This can also be the filename of a ruleset.