Upgrade Notes
When upgrading to [SpamAssassin] 3 4.10.x, it is _essential_ that you read \[http://svn.apache.org/repos/asf/spamassassin/branches/3.1/UPGRADE the SpamAssassin 3.1.x 'UPGRADE'\] file0, please read the Release Announcement and Upgrade Specifics to check out all the new features and identify any issues with upgrading. Wiki Markup
If you run into any problems, or some functionality appears to stop working, FrequentlyAskedQuestions should be the first port of call read that file (again). If it's not dealt with there, check FrequentlyAskedQuestions – especially the Installation and configuration... section.