After the introduction of separated minimum and maximum values for time between requesting a form and sending it back to the server the amount of new registrations that never got activated reached 0. Even spam postings seems to be absent in this forum at the moment.
In my more or less unknown own forum I see also no registrations but on the other hand I get around 40 to 50 spam postings per day. All of them get recognised (by Akismet, Bad Behavior or Stop Forum Spam) and hidden.
This is the current status. All spam messages arrived between 2019-01-21 15:00 and 2019-01-22 16:25.
My minimum of 10 seconds for sending back the posting form is obviously not enough. Micha introduced a Bayes-filter for version MLF 2.5 a a further spam prevention mechanism.
@Micha: Would it work with a experimental backport or should I upgrade to master branch of MLF?
Trenne niemals Müll, denn er hat nur eine Silbe!