+SquirrelMail themes directory:
+
+ $ cp -pi squirrelmail-1.4.8/themes/* squirrelmail-1.4.17/themes/
+
+
+F. Preferences
+---------------
+
+Chances are that, as long as you followed our installation recommendations,
+you don't need to make any changes for your user preferences. That is,
+if you have preferences stored in a database or you have moved your
+preference file storage outside the SquirrelMail directory (such as
+/var/lib/squirrelmail/data/) as explained in our installation documents,
+then you don't need to do anything.
+
+However, note that when upgrading between major versions (such as between
+1.4.x and 1.5.x), it is usually best to create a secondary preferences
+storage location and start with a fresh system for your users to configure.
+That said, many preferences are the same between versions and to date there
+are no known incompatibilities between 1.4.x preferences and 1.5.x preferences.
+
+If you have your preferences stored inside your old SquirrelMail
+installation, we'd STRONGLY encourage you to re-read our installation
+information and consider moving them away from the web server's reach.
+If for some reason you need to continue to store your preferences inside
+the SquirrelMail installation, you can move the new data/ directory out
+of the way and copy the old preferences to the new installation:
+
+ $ mv squirrelmail-1.4.17/data/ squirrelmail-1.4.17/data-new
+ $ cp -Rp squirrelmail-1.4.8/data/ squirrelmail-1.4.17/
+
+If you are using Windows or otherwise cannot use the commands above, please
+make sure that you preserve the permissions and ownership of the data/
+directory as you move it, since SquirrelMail will not work unless the web
+server has write permission in the data directory (which, presumably, your
+old data directory has been set up with).
+
+PLEASE NOTE: If you are upgrading from versions lower than 1.0.5, you
+are STRONGLY encouraged NOT to migrate preferences, since there were
+important security upgrades in the preferences system starting with
+SquirrelMail version 1.0.5.
+
+
+4. Run the configuration utility
+=================================
+
+Although not strictly necessary for minor upgrades, we STRONGLY
+recommend that you run config/conf.pl to see the new configuration
+options available with the new version, as well as to verify that
+all of your old options are set properly. In SquirrelMail versions
+1.5.2 and above, this also ensures that your plugins are properly
+registered with SquirrelMail.
+
+Always save your options, even if you haven't changed anything. This
+will ensure that any problems with your configuration that have been
+automatically detected and fixed are not lost.
+
+If you want to make sure that your configuration contains all themes
+included in new SquirrelMail package, go to theme options in
+configuration utility and run theme detection command.
+
+
+5. Visit src/configtest.php
+============================
+
+You should browse to http://example.com/squirrelmail/src/configtest.php
+(adjust the address to suit your system) and confirm that there are no
+configuration problems. Note that in versions 1.5.0 and up, you'll need
+to make sure $allow_remote_configtest is enabled in your configuration
+file to do so (or see "11. Tweaks" ==> "7. Allow remote configtest" in
+the configuration utility).
+
+
+6. Verify that the new installation works
+==========================================
+
+Log in and take a look around in your new installation and make sure
+everything is working as expected.
+
+
+7. Follow-up
+=============
+
+Once you've finished upgrading, you may want to keep an archived copy
+of your old installation just in case something goes wrong with the new
+one. You can simply move the whole directory somewhere else outside
+of your web server's document root or compress the directory into an
+archive file for storage elsewhere. Here's how to create a zip file
+of your old installation in a Linux-like environment:
+
+ $ cd /usr/share/
+ $ zip -r squirrelmail-1.4.8.zip squirrelmail-1.4.8
+
+Or to create a gzipped tar archive:
+
+ $ tar czvf squirrelmail-1.4.8.tar.gz squirrelmail-1.4.8
+
+Then make sure that you REMOVE the old directory so users can no longer
+access it - if you don't do this, you may be leaving yourself exposed
+to known security exploits.
+
+
+8. How to point the web server to different SquirrelMail installations
+======================================================================
+
+In this guide, we assumed that your installation directories looked
+like "squirrelmail-1.4.17". Most of the time, you'll want to allow
+your users to type in "squirrelmail" (or just "webmail" or "mail")
+without needing to know the version number. Of course, you can simply
+change the name of the SquirrelMail installation directory:
+
+ $ cd /usr/share/
+ $ mv squirrelmail-1.4.8 mail
+
+... but there are several more graceful ways you can achieve this.
+In any Linux-like system, you can use symlinks to dynamically point
+"webmail" to any of your version-specific installations:
+
+ $ cd /usr/share/
+ $ ln -s squirrelmail-1.4.8 mail
+
+Note that symlinks can point anywhere you need them to, so the installation
+directory doesn't necessarily need to be in the same place the "mail" link
+is.
+
+You can also configure most any web server to point to your installation
+directory from any incoming address you desire. There are several
+redirection and address re-writing tools for most web servers, so this is
+just one example using Apache's Redirect directive:
+
+ Redirect permanent /squirrelmail-1.4.17 https://example.com/mail
+
+
+9. Version-specific upgrade issues
+==================================
+
+Upgrading from the 1.4 release series to the 1.5 release series
+---------------------------------------------------------------
+
+The plugin API changed substantially in version 1.5.2. At the least,
+you should NOT copy your old plugins when making this kind of upgrade.