[pfx] Re: Question about postscreen_dnsbl_sites

2023-10-11 Thread Wietse Venema via Postfix-users
Ivan Ionut:
> Thx, but I noticed that there is only for cidr...and i want for 
> hosts/domains too.

If you want client name/domain based policies, don't use postscreen,
use smtpd_mumble_restrictions instead. 

An smtpd process can do complex things such as verifying fully-confirmed
forward/reverse DNS for clients in arbitrary domains, and making
nuanced decisions based on the combination of client, sender, and
recipient information.

postscreen is designed to answer only one question: "is this a
spambot". That is completely orthogonal to the question of whether
or not you like a client hostname.

postscreen cannot afford doing complex things. It must be able to
handle many more (like 10 times more) clients than hundreds of smtpd
processes combined can handle.

postscreen has to make a quick decision based on the client IP
address which is guaranteed to be available, and queries only the
domains listed in postscreen_dnsbl_sites, which are guaranteed to
respond quickly. postscreen WILL NOT query other domains because
there are no response time guarantees.

Wietse
___
Postfix-users mailing list -- postfix-users@postfix.org
To unsubscribe send an email to postfix-users-le...@postfix.org


[pfx] Re: Question about postscreen_dnsbl_sites

2023-10-11 Thread Wietse Venema via Postfix-users
Ivan Ionut via Postfix-users:
> 
> Hi, I'm using postscreen_dnsbl_sites to block some spam and I want some 
> domain/hosts/ip to bypass this option, like an whitelist.
> 
> Does postscreen/postfix has this option?
> 

Yes. Near the top of https://www.postfix.org/POSTSCREEN_README.html#quick

Quick tests before everything else

Before engaging in SMTP-level tests. postscreen(8) queries a number
of local deny and allowlists. These tests speed up the handling of
known clients.

* Permanent allow/denylist test
* Temporary allowlist test
* MX Policy test

See website for more.

Wietse
___
Postfix-users mailing list -- postfix-users@postfix.org
To unsubscribe send an email to postfix-users-le...@postfix.org