# If you want to keep your logfiles forever, turn this setting on. All
# logfiles will get suffix ".[day, 2 digits][month, 3 letters][year, 4 digits]".
# Note that your quota/hard-disk might be filled by this, so check your logfiles
# often and download them.
set keep-all-logs 1
# If keep-all-logs is 1, this setting will define the suffix of the logfiles.
# The default will result in a suffix like "04May2000". "%Y%m%d" will produce
# the often used yyyymmdd format. Read the strftime manpages for more options.
# NOTE: On systems which don't support strftime, the default format will
# be used _always_.
set logfile-suffix ".%d%b%Y"
Also netbots has a built-in that has the bot email your logs daily.