For now my spam problems are over. Preliminary to the improvements my webhost is making to provide enhanced spam filtering, they requested that all users turn off their “Nobody Alias”. This feature, when active, accepts all emails addressed to the domain and delivers them to the administrator’s email address - even if the email box doesn’t exist.
I had this turned on, and I had it turned on on purpose. I didn’t want to miss anyone e-mailing me about Behold who might have spelled the first part of my e-mail address wrong, e.g. firstname.lastname@example.org. I was willing to put up with the (currently up to) 2000 spam a day that come that way, just so I wouldn’t miss the one that really was meant for me.
But Myhosting asks I turn it off until they are ready to introduce their newly designed email system. So I shall, and I’ll have to put up with only a measley 50 spam a day for now. Oh horrors.