The Main Principles of Blacklisting: How to Avoid It?

According to Statista, spam occupies about 55% of total email traffic, so email services use spam filters and blacklists to protect customers from it. If you are making active mailings and notice that inbox delivery rates have begun to drop, your domain or IP address may have been blacklisted. In this article, we will tell you what it is and how not to get into them.

What Is a Blacklist?

A blacklist is some IPs and domains that have been blocked due to possible spamming. The purpose of blacklisting is to reduce the percentage of irrelevant emails sent to users. In general, there are two types of such lists:

  1. Based on the sender’s domain. 
  2. Based on the sender’s IP (IP blacklist database).

If the domain or IP is on the list, letters will not be delivered at all or will go through additional spam filters. Besides, the blacklists use different spam identification algorithms. For example, if a mailing list collects a lot of spam complaints, then the percentage of letters delivered to the inbox drops to zero.

How Do the Blacklists Work?


They use spam traps and complaint information to identify the IPs and domains that are sending suspicious emails. Spam traps are local email addresses that are located on various sites and forums to identify the senders of spam.

Spam traps are divided into two categories:

  1. Converted email addresses that have been inactive for over a year, which is why email services have turned them into spam traps;
  2. The classic baits – specially created email addresses. They are posted on popular resources where you can parse the address base for further sale or spamming.

All services have different ways of defining spammers. But almost all of them use a combination of spam traps and spam complaint data.

The operator can initiate adding to the black database an IP if it receives an excessive stream of complaints about sending spam. To avoid blacklisting, you need to ensure that mailings are sent to valid and active addresses.

Mail services refer to reputable repositories to verify the domains and IPs of the sending server. They ask for information about whether users have complained about spam.


How to Reduce the Risk of Being Blacklisted?


If you have an email or a dedicated server that you use for work, the below steps will come in handy:

  1. organize the subscription of new users through the double opt-in; 
  2. allocate separate IPs and clean the database from invalid addresses; 
  3. domains for different types of mailing; 
  4. provide the ability to unsubscribe from mailings quickly.

To keep a high sender’s reputation, we recommend you regularly check black databases and analyze mailing performance. Focus on the quality of your content, keep an eye on the technical settings of your emails, and you will be secured from blocking.

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