How to protect against postfix spam?

Question

postfix

Can you please tell me how to protect against spam on a mail server based on postfix?
Haven't done anything yet.
Reject in the absence of PTR by itself.
Almost a dozen DNSDBL
spamassassin
razor
pyzor
greylisting

Answer 1

from the usual:
do you check SPF?
spamassassin teaching?
have you tried postscreen?
have you tried amavisd?
from new:
DMARC can be tried.

Answer 2

Although with DMARC there are difficulties in building. I would recommend setting up an SPF check first, then spamassassin would come to grips with it. It must be constantly trained, but the effect is noticeable instantly and with the naked eye.

Answer 3

it's all great, but not quite right. I work in a publishing house. weekly. the nature of the mail going to the advertising department and considered so more or less normal, for users of other departments will be considered spam. therefore, when the issue of blocking spam arose, we took the measures listed by the author + installed maia mailguard. thus, each user gets access to his "office" through the web interface and decides for himself what is spam for him and what is not.
because maia mailguard is not developing, it might be better to look at mailscanner + there is a web interface for it (you can google it)
for a good result, the user should train the system regularly, at least once a week
, something like this