Now that Ive upgraded to 0.15 why is bogofilter working less well?
Prior to version 0.15.4, bogofilter added special prefixes to tags from “Subject:”, “From:”, “To:”, and “Return-Path:” header lines. As of version 0.15.4, “Received:” line tokens are also specially tagged and all other header line tokens are given a “head:” prefix. Since bogofilter hasn’t previously seen “header:” tokens, these tokens don’t contribute to either the ham or spam scores. This loss of information causes bogofilter to perform less well. There are two ways to deal with this problem. The first is simply to retrain bogofilter with all the old ham and spam. This will create the needed “head:” entries and all will be fine. The second is to use the new header-degen (“-H”) option. When classifying a message, header-degen causes bogofilter to look up both “head:token” and “token” in the wordlist. The two ham and spam scores are combined to give a cumulative result for scoring. Registering messages will create “head:token” entries in the wordlist. After a month or so of using ‘-H’,
