Here are a couple of programs who make a RFC compliant POP3 server.

 * popserv open a socket a act as a multithreaded autentification server.
   As possible, it try to keep socket and file openned. The authentified
   user may be logged to whoson or mysql server. Optionnaly, UDP packets
   may be send to specified unicast or multicast address.

 * popit is spawned for each authenticated user within his maildir
   directory with appropriate user permission. It manage POP3
   transaction and cleanup states.

* DOWNLOAD

You can get new version from the web site http://pll.sourceforge.net/

* INSTALLATION

The configure shell script try to guess what software are installed on
your server. Some options may be forced passing arguments :

   --without-mysqllog    disable MySQL logging
   --without-libhome     disable libhome support
   --without-whoson      disable whoson support

Once you configured the package, run "make" then "make install".

* CONFIGURATION

The configuration file, "popserv.conf" is typically in /usr/local/etc
directory. Manual page popserv(8) describe the options you may set.

If you configured it with libhome and libhome send uncrypted password,
you may enable apop support with the following configuration
directives :

  apop 1
  crypt 0

With libhome, the server may server multiple domains but as some POP3
clients may use internaly the '@' characted you should allow a
replacement character like '%'. This may be done with the following
libhome.conf directive :

  rewrite (.*)%(.*)       $1@$2

So, user%example.com become user@example.com.

The server allow to server other mail folder than default INBOX, bu
you have to specify a delimiter for that extension. For example :

  folder \+([^%@/]*)

So, the folder will be the string into the first parenthesis, if user
authentify himself as "user+foo@example.com", the server will serve
the "foo" mail folder of user@example.com.

The server "popserv" may be run as daemon with the furnished script
"popd.sh" or via inetd in wait mode :

  pop3   stream  tcp     wait    root  /usr/local/libexec/popserv popserv -i