I have several servers for mail. Some of them on postfix and some on sendmail.
Maybe a moth ago I started to have problems with spam.
I did not use dnsbl-s before. Now I am trying to use sorbs.net blacklists, but it seems that it cannot cache the most of them.

Do anybody know some good blacklist sources, it is really terrible what amount of spam traffic is on the network nowadays.

I do use now several dnsbls. They work well, with some little problems.
Lots of dynamic IPs, from where the clients connecting to my server are on the netblock list on spamhaus.org.
When I read about the listing, they tell that those clients should use SMTP AUTHENTICATION to avoid this problem.

My account do use SMTP AUTHENTICATION but there are still problems. My mail server shows logs like:
ruleset=check_rely, arg1=adsl-dyn22-22-22-22.telecom.sk, arg2=, relay=adsl-dyn22-22-22-22.telecom.sk [], reject=553 5.3.0 Relay refused ...

It is ok that it is refused, the IP ( example) is on their list. Spamhaus tells that each dynamic IP range should be blocked.
But what has to do the SMTP AUTHENTICATION with it.

Should the relay section be something else if the MUA authenticates the user with SMTP AUTH correctly.