The rebuildspamdb.pl script is used to rebuild your Bayesian spam / non-spam database. It reads through all the files in the spam, notspam, errors/spam, and errors/notspam directories and builds the statistical model that is used to test incoming mail. You can use your operating system's scheduling features to schedule it to be run periodically -- possibly daily or at least weekly. 

<sudo> perl rebuildspamdb.pl path/to/assp-base-dir

You may use the buildin schedule:
-Schedule time for RebuildSpamdb (RebuildSchedule)
If not set to 0 ASSP uses scheduled hours to run RebuildSpamdb.pl. For example '6|18' will run rebuildspamdb.pl at 6.00 and 18.00. Use 24 to run it at midnight.
