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Treasure of Knowledge About IP Blacklist

A blacklist is a real-time database ofdomains or IP addresses that have been identified to send spam or malicious content. Most Internet Service Providers check the blacklist databases to filter emails sent to the recipients within their network.

The outcome of having the sending IP address or domain on a blacklist can vary from being a small annoyance to a large block of your email campaigns.

To have better deliverability, email marketers ensure to have an understanding of why a domain or IP can get on a blacklist, what to do in case the IP is blacklisted, and what is the secret to avoiding getting the IP or domain on a blacklist.

How Do Blacklists Work?

Internet organizations like, Mail Abuse Prevention Systems, observe all IP addresses and domains that energetically send emails and produce databases of IP addresses/domains that are recognized in some way to be used to send spam. ISPs can utilize these databases when filtering email messages from a sender. It is a significant step to protect mailbox owners from spam.

When you send an email message, your sending IP address, which is the IP address of the SMTP server you use, is logged. It permits the receiving mail servers to determine who is sending the email message and check if that source has been known to send bad or good emails, by referencing the blacklists’ databases.

Below is the process:

  1. You forward an email from to Harry.
  2. Harry’s mail server determines your sender’s IP address (for example, and resolves it into a domain name.
  3. Harry’s mail server checks both the IP and domain against a database of IP/domains in a blacklist.

In case the IP address or the domain is blacklisted, then your email will probably land in Harry’s spam/junk mail folder without the content of the email being scanned.

In case the IP or domain is labeled as a repetitive spam sender, the ISP’s spam filters will discard your message, meaning it won’t even reach Harry’s spam folder.

How Did My IP Get Blacklisted?

Open relay servers, hosts on particular sites, email spamming software, etc. are frequently added to blacklists. Some blacklists incorporate IP addresses and domains based on user reports of unsolicited emails, for example, complaint rate.

Spam complaints occur for very different reasons:

  1. A receiver didn’t subscribe to the list;
  2. A receiver didn’t find the unsubscribe link;
  3. A receiver forgot opting it to the list;
  4. A receiver receives so many emails;
  5. Content is not relevant to the recipient’s assumptions;

A little complaint rate (<0,01%) is acceptable. Although the number of complaints is higher than the allowed threshold, mailbox providers may begin filtering the email messages to the spam folders or blocking the emails altogether.

Bad email list hygiene can also lead to blacklisting problems. Sending messages to inactive or old email addresses that could have been turned into spam traps, or harvested email ids that are potential spam traps is destructive to your sender reputation.

Spam traps divide into two categories:

  1. Recycled spam traps.These are email ids that were valid email accounts but have not been engaged with any email message for a long time. The receiving server usually returns emails sent to these ids for a year or more before the recycled email accounts are rebooted as spam trap addresses.
  2. Pristine traps.These are email ids that are set up by anti-spam organizations and ISPs with the only motive to determine spammers. They have never been used to sign-up to amailing list. Pristine traps most usually get on mailing lists when senders rent, purchase, or harvest addresses.

How to De-List IP or Domain?

It is essential that you have to begin by seeing which blacklists your domain or IP is on. Various blacklists have a different influence on email deliverability. Being listed on extensive blacklists (Spamhaus, SORBS, SURBL) will most possibly lead to a spam placement or a complete email block while listings on small local blacklists can have zero impression.

When you don’t get bounced emails because your sending IP or domain is blacklisted and the inbox testing delivery report displays a high inbox rate, then blacklists are not likely to impact your sender reputation. In the opposite case, blacklisting problems must be addressed.

Keep in mind that you can de-list your IP only if you own that IP. If you send emails messages from a pool of shared IP addresses that belong to an email service provider (ESP), then you can only report the blacklisting problems to your ESP.

At DNSBL websites, you can input your IP to check your IP status, and then follow the directions on how to be eliminated. A lot of blacklists have a manual de-listing procedure. A few will do it automatically after some time.

The trick is to be proactive. Detect and solve the problems that got you to a blacklist (check your email acquisition sources, eliminate inactive users, authenticate the message content) before you communicate the blacklist’s owner. They like to observe that you’re taking it seriously and attempting to solve your delivery challenges in a timely fashion.It is significant to remember these things when applying for a de-listing:

  1. Don’t argue or dispute. Focus on the facts they offer you and use the remedies.
  2. In case you are a repetitive abuser, you will find it tough, if not impossible, to be de-listed.
  3. If you know the reason for a listing, solve it first, and then apply for de-listing.

How Do I Not Get Blacklisted?

Evenlegitimate email senders can end-up in a blacklist because of their email sending habits. Although, via best email marketing practices, you will significantly decreasethe risk of being blacklisted.

Here are some simple guidelines to follow:

  1. Don’t buy or scrape email addresses.Instead, create your mailing list organically to make sure you are not hitting spam traps.
  2. Don’t forward to email lists rented from 3rd party organizations even if you have the same offer. Those individuals didn’t subscribe to your emails and are possibly report your email message as spam.
  3. Use a confirmed opt-in process. You may end-up with a minor list, but you successful in quality. The approved opt-in process guards you against bots, spam traps, malicious subscriptions, and invalid email addresses caused by human typos.
  4. Remove inactive email addresses regularly. In case a receiver has not engaged with your emails for the previous 90 days, exclude their email address from your email list to avoid sending it to a recycled spam trap.
  5. Monitor subscriber complaints. Subscribe to feedback loops where it is possible to get email notifications when someone reports your email message as spam. Eliminate complaining users from your time to time.
  6. Add an unsubscribe link button to a prominent place. Ensure that the unsubscribe procedure is working, and the receiver will not receive any further email messages from you.
  7. Send only those content that is relevant to the receiver. If you have different mail streams (newsletters, promotions, product-related campaigns, etc.) and allow users to choose the email lists to subscribe, then don’t send all emails to all receivers. Respect their choice.
  8. Don’t send emails too much or too l Find the most significant frequency in order to not overload the receivers and to not let them forget you. The most extraordinary thing is to send as many email messages as you promised on the subscription form.

You have to remember that blacklists are not created to make the life of email marketers a nightmare. They are here to protect email receivers and help them get the messages they want. If you are giving your 100 percent efforts to send relevant email messages to confirmed subscribers, it will decrease the risk of getting on blacklists to a minimum and will create the procedure of getting de-listed much easier.

Always Run A Spam Test

Spam filters are continuallydeveloping and learning. No measure will guarantee deliverability for a lifetime. It indicates you have to always test your email spam score, IP address, and email placement before you deliver an email campaign.

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