Every day, a lot of people use email. It’s one of the keys for quick and easy communication.

Unfortunately,聽junk聽mail,聽more聽commonly聽known聽as聽spam,聽is one of the聽big聽problems聽of聽the聽email.

With hundreds of spam in your inbox, you聽can聽lose聽the聽important聽email.

That鈥檚 why, we often get requests from our clients to prevent spam on the server as part of our Server Management Services.

Today, we’ll see how our Support Team prevent spam by setting up “DNS Blackhole Lists in Plesk”.

First, let’s understand further on DNS Blacklists.

DNS Blacklists or DNS Blackhole Lists (DNSBL) is a service that contains a set of IP Addresses that are involved in Spam activities.

Nowadays, most of the mail servers have configured to reject or flag messages when sent from an IP listed in DNS Blackhole Lists.

Plesk provides many methods for spam protection. It includes features like

However, many servers still face spam problems. That’s where DNS Blackhole Lists (DNSBL) has a major role to play. This is one of the options that our Dedicated Engineers recommend to customers with Plesk servers.

Recently, our customer approached us with the problem like “they are getting a lot of spam emails” in their inbox. Customer had setup Plesk control panel in his server.

Even though they had configured SpamAssassin in Plesk, they were getting a lot of spam emails in the user’s mailbox.

Let’s see how our Support Engineers used DNS Blackhole Lists in Plesk to prevent spam on the server.

1. The very first step we did was to check the logs, to verify if they were really receiving any junk emails.

2. We found that there were suspicious emails. We could see that many mails originated from bad IP addresses. That’s why, we decided to enable Blackhole lists on the server. We performed the following steps to enable DNS Blackhole Lists.

With that DNS Blackhole Lists was enabled on the server. Then, the logs started showing errors like 550 (connection refused). Thus, it denied the messages from black listed IP addresses.

From our experience in fixing the issues with DNS Blackhole Lists, the following are some of the related errors our Support Team found so far.

This error happens when you incorrectly type the entry in DNS zone for DNSBL service. It results in “This is not the DNSBL you’re looking for” error.

Often outdated SpamAssasin create problems with DNS Blackhole Lists. Your SpamAssassin version should be upgraded if it’s an old version, only then it queries DNS zone entry listed in DNS Blackhole Lists.

There can be cases where the Blackhole lists do not block any mail on the server. This happens when there are problem with DNS resolvers on the server.

To fix it, our Dedicated Engineers add Google Public DNS (8.8.8.8) in the resolvers list.

[Trouble with DNS Blackhole Lists? Our Plesk Engineers can fix it for you now.]

To be more precise, “DNS Blackhole Lists” is a powerful tool to avoid spam activities like junk and malicious emails. Today, we saw how our Technical Team set up “DNS Blackhole Lists in Plesk” to fight against Spam.