Stopping backscatter with D_REJECT

[Michael Orlitzky]

On 04/17/2017 09:00 AM, Todd D. Taft wrote:
> I was hoping to avoid dropping messages on the floor for well-behaved
> servers.  While it's rare, I have found the occasional ham that gets
> marked as spam.  With D_REJECT, at least the sender gets a notification
> that the message didn't go through.

You can put amavisd-new in front of postfix, acting as a proxy:

   http://www.postfix.org/SMTPD_PROXY_README.html

In particular, the pros and cons of that approach are listed here:

   http://www.postfix.org/SMTPD_PROXY_README.html#pros_cons

Doing so lets you reject spam immediately, but the trade-off is that it 
requires more resources because you can't just queue up messages for 
later scanning.

(This is "not supported" by amavis, but works just fine.)