To activate SquirrelMail, you must complete the following steps:

1) Set up a VirtualHost or an alias in httpd.conf that points to
   %%SQUIRRELDIR%%

2) Make sure the following is set in your php.ini:
   file_uploads = On

3) Configure your installation.
   SQUIRRELMAIL WILL NOT WORK UNTIL THIS HAS BEEN DONE.
   cd %%SQUIRRELDIR%% && ./configure

4) It is best practice to change the data/user preference directory
   (under General Options) to somewhere outside of
   %%SQUIRRELDIR%%.