INTRODUCTION
 
 v0.20.0 is a major update to POPFile with the focus being on performance.
 In addition POPFile makes another leap forward in support for non-English
 languages with many new UI translations (including our first right to 
 left language) and full support for parsing of Japanese and Korean.
 
 v0.20.0 is intended to end-of-life v0.18.x and v0.19.x.  All future 
 development work will be occurring around the v0.20.0 line of code and no
 bugs will be fixed against previous versions.  A lot of work has gone
 into making v0.20.0 the version of POPFile to have.
 
 To improve POPFile's performance the following changes have been made:
 
 1. The corpus (where the word lists are stored) has been changed from a
    flat text file to a BerkeleyDB database.  When you run POPFile v0.20.0
    for the first time you will see your existing corpus get automatically
    upgraded to the BerkeleyDB.
 
    (See the 'license' file for details of BerkeleyDB's license)
 
    The use of the database both speeds up POPFile (especially the
    reclassification process which has slowed down in v0.19.x) and reduces
    its memory requirements.
 
    The time to load the corpus has now gone from minutes/seconds to close
    to zero.
 
 2. The history data is cached between sessions.  If you regularly start and
    stop POPFile (e.g. you start and stop your PC every day) then you'll
    notice another load-time speedup: the history data is being cached 
    between POPFile sessions to make loading faster.
 
 3. The history is progressively updated.  As messages are downloaded from
    a server POPFile used to store all the messages for insertion into the
    history the next time the history was viewed.  Now as messages are 
    downloaded they are inserted in to the history progressively.
 
 4. When viewing a colored message you'll notice a big speedup because there
    were previously two scans through the message (one for classification
    and one for coloring) this is now reduced to one.
 
 5. When downloading messages we previously saved the message to disk and 
    then reloaded it for classification.  Now the mail parser has been 
    modified so that the text of the message is streamed into it as it is
    read from the mail server and classification happens in line without the
    need to reread from disk.
 
 6. On Windows the default configuration for the proxy is to no longer fork()
    the server.  This means that downloading mail starts very quickly, but
    has the downside that only one email account can be checked at a time
    and the UI cannot be used during download.  This new option is controlled
    by a configuration parameter (-pop3_force_fork) and through the UI.  On
    non-Windows platforms POPFile will fork() each new connection.
 
 To improve POPFile's stability:
 
 There's been a huge effort to write a complete test suite for POPFile.  
 Currently we have tests that cover 99% of POPFile's code (i.e. almost every 
 line of code is exercised by a test) and the plan going forward is to try 
 to keep it that way.
 
 The test suite exercises the UI as if it were a user clicking buttons and
 submitting forms, it includes a complete POP3 server and client so that the
 proxy functionality can be tested and contains hundreds of tests for mail
 parsing.  
 
 Every module has an equivalent TestFOO.tst that tests it, if you are interested
 in running the test suite get the tests/ directory from CVS and run 'gmake
 test'.
 
 To improve POPFile's accuracy:
 
 A number of bugs have been fixed that sometimes caused POPFile internally to
 get the right classification and then insert the wrong headers.  The mail
 parser has been updated with the latest spammers' tricks and new pseudowords
 and we've done an experiement with 'unsure' classifications and decided to
 ship with code that will mark a message as 'unclassified' if it isn't 100
 times more certain it's in bucket A than bucket B.  This should reduce the
 false positive rate a little at the expense of POPFile saying it's not sure.
 
 
 ESSENTIAL READING IF YOU ARE UPGRADING TO v0.20.0
 
 1. BACK UP YOUR OLD INSTALLATION: POPFile makes this really easy, just copy
    the entire POPFile directory somewhere.  You can then safely install
    POPFile v0.20.0 on top of your current installation; I just think a back up
    is a sensible precaution.
 
 2. IF YOU ARE RUNNING WINDOWS: Please read the section below I AM RUNNING
    WINDOWS AND NEED TO CHECK MULTIPLE EMAIL ACCOUNTS SIMULTANEOUSLY
 
 3. ON WINDOWS POPFILE IS NOW AN EXE.  Windows users will now be able to see
    POPFile running in the Task Manager with an executable called popfileXX.exe
    where the XX is one of f, if, b, ib depending on configuration.  POPFile
    is started by running popfile.exe which chooses the appropriate popfileXX.exe
 
    This might cause your firewall to ask about giving popfileXX.exe permissions, 
    in addition if you had allowed Perl permissions in your firewall they are
    NO LONGER needed.
 
 4. The installer will cause POPFile to run in the foreground if the database
    upgrade is required so that the upgrade process is evident to the user. 
    Once upgraded you can switch to background my going to the Configuration
    tab and changing "Run POPFile in a console window?" to No.
 
 
 I AM RUNNING WINDOWS AND NEED TO CHECK MULTIPLE EMAIL ACCOUNTS SIMULTANEOUSLY
 
 Because the time taken to start a new process on Windows is long under Perl
 there is an optimization for Windows that is present by default: when a new
 connection is made between your email program and POPFile, POPFile handles it
 in the 'parent' process.  This means that the connect happens fast and mail
 starts downloading very quickly, but is means that you can only downloaded
 messages from one server at a time (up to 6 other connections will be queued
 up and dealt with in the order they arrive) and the UI is unavaiable while
 downloading email.
 
 You can turn this behavior off (and get simultaneous UI/email access and as
 many email connections as you like) by going to the Configuration panel in
 the UI and making sure that "Allow concurrent POP3 connections:" is set to
 Yes, or by specifying -pop3_force_fork 1 on the command line.
 
 
 I AM USING THE CROSS PLATFORM VERSION
 
 POPFile requires a number of Perl modules that are available from CPAN.  New
 in v0.20.0 are the need for the following:
 
  BerkeleyDB
  Text::Kakasi (if you want Japanese language support)
  Encode       (if you want Japanese language support)
 
 
 I LIKE TO LIVE DANGEROUSLY
 
 In a future version POPFile will add official support for message classification
 through the SMTP and NNTP (Usenet news) protocols.  There are currently proxy
 modules for these protocols that work with v0.20.0, but they have not been 
 fully tested.  If you are interested in getting them get them here:
 
 http://cvs.sourceforge.net/viewcvs.py/*checkout*/popfile/engine/Proxy/SMTP.pm?rev=1.22
 http://cvs.sourceforge.net/viewcvs.py/*checkout*/popfile/engine/Proxy/NNTP.pm?rev=1.21
 
 and place them in POPFile's Proxy/ directory.  
 
 
 DOWNLOADING
 
 You can obtain the latest releases of POPFile by visiting
 
     http://sourceforge.net/project/showfiles.php?group_id=63137
 
 
 UPGRADING
 
 Just install POPFile on top of the currently installed version.  But did you
 read the ESSENTIAL READING above first.
 
 
 INTERNATIONALIZATION
 
 POPFile's support for non-English languages has grown and the UI is now
 localized into 26 languages:
 
         Bulgarian
         Chinese (simplified)
         Chinese (traditional)        
 NEW     Czech
         Danish
         Dutch
         English
         English (UK)
         Finnish
         French
         German
 NEW     Greek
 NEW     Hebrew
         Hungarian
 NEW     Italian
 NEW     Japanese
         Korean
         Norwegian
 NEW     Polish
 NEW     Portugese (Iberian)
         Portugese (Brazilian)
         Russian
         Slovak
         Spanish
         Swedish
         Ukrainian
   
 Also added support for understanding Japanese and Korean and doing word
 splitting correctly.
 
 DONATIONS
 
 Thank you to everyone who has clicked the Donate! button and donated their
 hard earned cash to me in support of POPFile.  Thank you also to the people
 who have contributed patches, feature requests, bug reports and translations.
 
     http://sourceforge.net/forum/forum.php?forum_id=213876
 
 
 CONCLUSION
         
 Keep the ideas and bug reports coming.  If you are interested in knowing 
 more about what's planned for future POPFile versions (or just learning
 about POPFile's history) visit the POPFile Roadmap:
 
 http://sourceforge.net/docman/display_doc.php?docid=17906&group_id=63137
 
 John.