Wow!  You've done considerable work on this since 2014 when I last downloaded it.  I'm looking forward to digging into it. 

Thank you!

In the downloads area of the site is a POP3 anti-bruteforce daemon posted by PetrJaklin.  It's specific to MercuryP but I sure could use such a daemon for MercuryS.  Anyone know of such? 

Is there is an alternative to adding an IP address range to the Content Control refuse list when repeated blocks of failed attempts are noticed? 

The current version of my smtpevt daemon has an option to block IP addresses that repeatedly fail to authenticate. Limit for number of failures within a specific time can be set in the ini file, and if you use the daemon blacklist blocking time is configurable as well.

If you want to have a look at it it's available here: http://downloads.serieguide.se/SmtpEvt.zip