Why is the IP DNS Blocklist not blocking emails?

Overview

You receive emails that are obvious SPAM but are not blocked by the IP DNS Blocklist.

Solution

The first step is to determine why these emails were allowed. To do so, please follow the steps described in the "Determining why the IP DNS Blocklist Filter Blocked or Allowed a Message" article.

If emails are allowed through, it is because none of the configured blocklists have recognized the sender as a spammer. In this case, you have the following options:

• Update IP DNS Blocklist configuration
• Blacklist the sender

Update IP DNS Blocklist configuration

You can make sure that the IP DNS blocklist is configured for optimal coverage. In MailEssentials go to the IP DNS blocklist. Ensure that bl.spamcop.net and dul.dnsbl.sorbs.net are enabled.

• Type zen.spamhaus.org in the Domain box and click Add IP DNS Blocklist.
• Type b.barracudacentral.org in the Domain box and click Add IP DNS Blocklist.
• Type dnsrbl.org in the Domain box and click Add IP DNS Blocklist.
• Type dnsbl.sorbs.net in the Domain box and click Add IP DNS Blocklist.
• Type truncate.gbudb.net in the Domain box and click Add IP DNS Blocklist.
• Ensure the new lists are enabled and click Apply.

Blacklist the sender

Alternatively, you can blacklist the sender, by using the available Blacklists:

1. Open the MailEssentials Configuration UI
2. Navigate to Anti-Spam > Anti-Spam Filters > Email Blocklist:
   1. Enter the sender's email address or their domain (i.e. *@spammer.com) to be added to the blocklist.

   2. Specify the email type to match for the emails to be added to the blocklist.

      Note

      For more information about the difference between SMTP and MIME refer to the "What is the difference between SMTP and MIME?" article

   3. (Optional) Enter a description for the entry in the Description field.
   4. Click Add.
3. Alternatively, if you know the sender's IP, navigate to Anti-Spam > Anti-Spam Filters > IP Blocklist:
   1. In the IP Blocklist Entry box, specify the IP addresses to block.
   2. Click Add to add the specified IP addresses to the IP Blocklist box.

Testing

After applying the steps above, spam emails should not reach your users' inboxes.