With the text editor chosen under general settings the score file for incoming mails can be changed. The possibilities goes from divert mailing lists in local groups to sort mails on the base of sender and delete by size etc or the list of the local receivers and other similars.
The explanations to the filter syntax can be found in the help to the file "MailFilt.hst".
For comfortable and orderly editing of scripts and score files there exist Syntaxshemata. These are templates for respective editors with different components of the syntax to colour them differently. Addition indications can be found in the Hamster script-archive: http://home.t-online.de/home/micha-wr/hamster/ (German Site).