POPFileD (http://popfiled.markmatrix.com/) is a Mercury/32 Daemon that allows Mercury/32 to call POPFile to examine mail. This allows Mercury/32 to serve as the direct interface both to the Internet and to the mail reader clients, without having POPFile acting as a proxy.
Installing POPFileD involves, amongst other things, installing a special proxy module (MERC.pm) in POPFile's "Proxy" directory. This new module results in changes to the UI's CONFIGURATION and SECURITY pages and some additions to the popfile.cfg configuration file (and hence the ADVANCED page in the UI).
At present the following versions of POPFileD are available:
POPFileD 1.0.1 (compatible with POPFile 0.20.x)
POPFileD 1.1.0 (compatible with POPFile 0.21.x)
POPFileD 1.2.2 (compatible with POPFile 0.21.x)
POPFileD 1.22.4 (compatible with POPFile 0.22.x, 1.0.0, 1.1.0)
If the POPFile 1.1.1 installer is used to upgrade, say, an existing 0.21.1 installation which has POPFileD installed then POPFile will not work properly after the upgrade (e.g. the UI will crash if an attempt is made to access the CONFIGURATION or SECURITY pages). See the "POPFile crashes when opening security tab in UI" topic in the HELP forum for details.
All four versions of MERC.pm include some version information so the Windows installer could be modified to check for an incompatible version, display a suitable warning and even disable POPFileD. (The installer already includes checks on which optional POPFile components are installed so that might be a good place to also check for POPFileD?)