spamassassin not lethal anymore

[Kurt Buff]

Snippety snip...

On Wed, Jan 11, 2017 at 4:13 PM, Russell L. Carter <rcarter at pinyon.org> wrote:
> On 01/11/17 14:05, Steve O'Hara-Smith wrote:
>>
>> On Wed, 11 Jan 2017 13:45:47 -0700
>> "Russell L. Carter" <rcarter at pinyon.org> wrote:
>> most of it botnet sourced. I've pretty much eliminated it now by a
>> combination of installing dcc and razor plugins to spamassassin (reduced
>> the spam getting through by 70% or so) and adding a backup MX with a free
>> service that only accepts messages to relay when the primary is down (it's
>> amazing how much spam stopped coming in when I did that).
>>
>
> I'm not sure what you mean here, can you elaborate a bit more?  I can
> do anything I like with my MX hosts so I'm game.  I *think* I'm
> already doing that. I have multiple domains, and so I have a primary
> MX and a couple of backup MX hosts (one of which is effectively a
> passive dovecot replicator, lordy that works fantastic).  The backup
> MX hosts are lower priority than the primary.  Are you doing something
> different?

A secondary MX that refuses mail when the primary is up and running
foils one of the favorite tactics of spammers - they will often target
the secondary MX because those are often not as up to date with
anti-spam measures. Most spambots try one MX, one time only.

Many spambots will try that secondary MX, get refused with a 4xx
error, and not bother to try the primary MX at all.

It can be a big win, in the right situation.

Kurt