[CentOS] Postfix restrictions

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
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-- 
-john r pierce
  recycling used bits in santa cruz