yeah, then don't use a backup MX server at all. I dropped using one when I realized most spam prevention would just end up at the backup which didn't have the same rules as long as your server has a decent uptime and is never down more than a few hours and that very rarely, then you really don't need a backup server at all. On Mon, Jun 8, 2020 at 7:57 PM Jon LaBadie <jcu at labadie.us> wrote: > 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 > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > -- -john r pierce recycling used bits in santa cruz