On Sun, Jun 07, 2020 at 05:53:28AM -0700, John Pierce wrote: > On Sun, Jun 7, 2020, 2:47 AM Nicolas Kovacs <info at microlinux.fr> wrote: > > > .... > > My aim is simply to eliminate as much spam as possible (that is, before > > adding > > SpamAssassin) while keeping false positives to a minimum. > > > > The one thing that stopped the most spam on my last mailserver was > greylisting. Any mta that connects to you to send you mail, you check > against a white list, and if they are not on it, you reject the connection > with a 'try again later' code and add them to a grey list that will let > them in after 10 minutes or so. The vast majority of spambots don't queue > up retries, they just move on to the next target. > > The downside of greylisting is delayed delivery of mail from non white > listed servers, dependent on their retry cycle. I hit another limitation. My backup MX handler is a 3rd party who will not use greylisting. Thus all the 1st timers I rejected just delivered to my alternate MX address and were not blocked at all. Jon -- Jon H. LaBadie jcu at labadie.us