Why blocklists are amateurishness

How many times have the world been told ... (c) Krylov IA

The story in this topic will go about monitoring the operation of the mail server in the same trade organization. And about the interesting observations about various BL, made in the process of this monitoring.

So: we have a small trading company that also organizes various training seminars. We have a gateway for this organization running on Ubuntu and iptables . We have a mail server within the organization’s network, which is configured absolutely correctly and works without any complaints. On the gateway , port 25 is blocked by all but the mail server. On the mail server for all the time of his work, not a single attempt of unauthorized access of any program or virus was noticed. Still, the organization falls with enviable regularity in the blocklist.
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To begin with, the stream of swearing at the address of individuals who set up mail servers. Anything can happen and someone can actually start sending spam due to a virus or an oversight. Very quickly, this someone will understand that he has a problem, thanks to the cuts about unsent letters from his server. Well, we climb into the logs and see there is:

host emx.infobox.ru[92.243.91.50] said: 550 5.7.1
    Recipient not authorized, your IP has been found on a block list (in reply
    to RCPT TO command)

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host imx1.rambler.ru[81.19.66.235] said: 554 5.7.1 Client host [xx.xx.xx.xx] blocked using xbl.spamhaus.org; http://www.spamhaus.org/query/bl?ip=xx.xx.xx.xx (in reply to RCPT TO command)

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