What Is an Email Blacklist?
An email blacklist is a list of IP addresses and domains associated with spam activities. Such real-time lists are used by internet service providers (ISPs) and mailbox providers to protect users from spam. If you send emails to spam trap addresses, or your campaigns generate a high number of complaints, you will soon end up on one or more blacklists.
Being on a blacklist comes with drastic consequences. The delivery rate of your emails can fall by a significant margin, since mail servers usually either greylist emails from blacklisted sources or block them entirely. Thus, it’s important to know what to do to avoid getting blacklisted. This article covers the basics of blacklisting and also gives you a clue what to do if you are already blacklisted and need a way out.
Types of Blacklists
If a particular IP address is registered as a major spam source, it’s generally safe to assume that all emails originating from that IP can be regarded as spam. A blacklist keeping track of such IPs is called an IP blacklist, or IPBL for short.
Since spammers may use different IPs, it is often more practical to block them by the sender’s domain name. Such lists are known as DNS blocklists, or DNSBL.
Other methods of fighting spam are associated with more complex analysis of the messages. For instance, an otherwise good-looking email may contain links that are known to be malicious. To prevent such emails from reaching inboxes, a dedicated type of blacklists has emerged, an URI blacklist (URIBL).
How to Not Get Blacklisted
These are the most important steps to take in order to avoid getting on a blacklist:
- Use a good email list. Build a legit email list consisting of addresses that opted in to receive messages from you. Avoid purchasing or exchanging email lists because people on those lists didn’t consent to your messages and will likely report you for spamming.
- List cleaning. You should regularly check your email lists and remove expired addresses or those that aren’t interacting with your messages. This improves your open rate and reduces the chances of being marked as a spammer. Keep in mind that some mailbox providers may use abandoned addresses as honeypots.
- Email content. The content of your messages should be engaging. You can use personalization to make it unique for every recipient. Sending out the same message to everyone on your list may bring about spam complaints. You can segment your lists according to common interests and send more targeted messages to each one.
- Timing. Don’t send emails too often because that’s the hallmark of spammers. Have a schedule and follow it. It could be weekly, bi-weekly, or monthly.
If You Are Already Blacklisted
Adhering to the steps we mentioned above minimizes the chances of getting a blacklist. But, let’s say you still got on one. What should you do? The first thing is not to panic. The problem may still be resolved.
There are hundreds of blacklists, and your IP address or domain might have landed on any of them. If it’s a small list, you’re safer because big ISPs and email providers don't tend to use them. If it’s a large list from a major cyber vendor, then it’s more of a problem.
If your personal IP address was flagged, you’ll need to contact the blacklist’s owner requesting removal. The good thing is that blacklist owners provide information on their websites about what steps to take to get removed from their lists. It usually involves correcting whatever issues they identified with your IP address and filing a request for removal.
In some cases, you may not even need to contact blacklists directly. Just continue mailing and avoid getting more spam complaints, and your IP address will likely drop off from the list after a short period.
If you're using an email service provider (ESP), they'll tell you what you need to do to remove yourself from a blacklist, or they'll reach out to the blacklist vendor themselves. However, your account may be suspended until you do what you were told to.
Most Important Blacklists
As we’ve said, there are hundreds of blacklists, and your IP address or domain could get listed on any of them. Some are more important than others, the ones used by top ISPs and mailbox providers. Getting into one of these will pose an urgent problem because it can sink your email delivery and open rates. Others may be taken less seriously as they may be used only by a small number of entities, or even, in rare cases, maintained for the sole purpose of offering “delisting services” for a fee.
The most notable blacklists to monitor include:
Spamhaus Block List (SBL)
What Is Spamhaus?
Spamhaus is an international organization founded to track spammers across the web. It supplies real-time blacklists to major internet networks and works closely with governmental agencies. Thus, getting on this list can tank your email reputation.
How to Resolve
Head to its official Blacklist Removal Center. You'll first need to run a blocklist check for your IP, and it’ll show you details on why it was blocked and tips to solve the issue. Ensure you take appropriate measures, and then you can fill out a form to request removal from the list. The process may take up to 24 hours after submission.
What Is Uceprotect?
Uceprotect is a DNS blacklisting service that lists anyone who sends messages to its spam traps. A spam complaint from a Uceprotect member may also get you on the list. It has three levels of blacklisting with increasing severity.
How to Resolve
The process of removing your address from the list depends on the level at which you were added.
- Level 1. Automatic delisting will occur in 7 days after the last spam message.
- Level 2. Removal can only be requested by your email service provider.
- Level 3. Automatic removal of your email service provider will take place only as soon as they no longer match the listing criteria.
What Is Barracuda?
Barracuda Networks is a well-known cyber software vendor. Since 2008, it has maintained a public Barracuda Reputation Block List (BRBL) that identifies IP addresses associated with spamming. It's one of the most reliable blacklist vendors with low rates of false positives.
How to Resolve
Head to the Removal Request section of Barracuda’s website and fill out the form. You'll have to provide your email server's IP address, your email address, your phone number, and a clear reason for your removal. It processes requests within 12 hours of submission.
What Is Proofpoint?
Proofpoint is another well-known cybersecurity vendor. It offers a blocklist service for ISPs, email providers, and organizations to identify IP addresses associated with spam and thwart them. The company blocks IPs ranges that are sending spam, IPs that send messages to its spam traps, and IPs with high numbers of spam complaints.
How to Resolve
The first thing required to remove your IP from the Proofpoint list is to head to its official IP removal page. Check your address to see if it's blacklisted, then fill out the form to request your removal and wait for a response.
What Is Cloudmark?
Cloudmark is an email security platform owned by Proofpoint. It offers threat protection to email providers and enterprises by identifying IP addresses affiliated with spam and blocking it from their networks. It serves dozens of ISPs such as Comcast and Cox as well as many mobile networks and hosting providers.
How to Resolve
Head to Cloudmark’s IP Reputation Remediation Portal and fill out the form. You'll need to provide your contact details and a compelling reason for your IP address to be removed. If the company accepts your reason, it'll reset your IP's status and remove it from the list.
What Is Abusix
Abusix is a German internet security company. It offers blocklists of IP addresses and domain names that email providers can easily integrate. The company has a formidable spam trap network and claims one of the highest spam detection rates (99.6%).
How to Resolve
Head to Abusix’s Lookup and Delist service. Check if your IP or domain has been blacklisted and click on the "Remove from List" button. The button will redirect you to a user portal where you can follow specific instructions to delist your IP or domain immediately. Note that you’ll need to create an account on the portal.
Many people don’t pay enough attention to blacklists and are at a loss when they notice a significant drop in their email delivery and open rates. Getting on a blacklist can pose a severe problem for your brand, which is why you must understand them and be careful to avoid them.
You must also know what steps to take if your IP or domain has been blacklisted. Different blacklist vendors require different steps to delist, but following them is usually straightforward. In all, ensure you pick a reputable email service provider, like UniOne, that will help you avoid the problem.