Email Blacklist Check: How to See If You’re on One

The Warmup Inbox Team
The Warmup Inbox Team

(Note: Some have started using the term “blocklist” in place of “blacklist” because of negative associations with the word. Both words have the same meaning and can be used interchangeably.)

What Is An Email Blacklist?

An email blacklist is an online collection of IPs or email addresses with severely damaged sender reputations. Mail servers use these lists as a reference to determine how safe it is to accept messages coming from unknown domains and addresses. Most blocklists are created to protect consumers from receiving malicious or unwanted emails.

Of course, if you’re on a marketing team, sending out malicious content is the last thing on your mind. But if your email address ends up on a blacklist for any reason, your emails won’t get to your subscribers.

When you send an email, the recipient’s server checks your IP address against multiple DNS blocklists. If your address doesn’t match any on a blocklist, the ISP will run a few other security checks to see which folder to put your message in. However, if there is a match on one of the lists, the ISP will not let your message through. Because a blocklist can put a full stop to your email marketing efforts, it’s crucial to ensure you’re staying off blocklists and keeping your reputation in good standing.

How To Check If You’re On An Email Blacklist

There are multiple online tools you can use to check if your IP address or domain is on a blocklist:

  • Barracuda Reputation Block List: free DNS blacklist that lists emails known to send spam
  • Invaluement:anti-spam DNSBL that blocks senders who send out unsolicited mass emails
  • MXToolBox:a way to check multiple blacklists quickly and check your DNS
  • MultiRBL:free multiple DNS service that cross-references lists by IPV4, IPV6, or domain
  • SpamCop:a list of IPs that have been reported as spam by SpamCop users
  • SpamHaus:DNSBLs used to identify and track spam sources
  • SURBL:lists of websites that have appeared in unsolicited messages
  • Warmup Inbox: as a part of our platform, we constantly run checks to make sure you’re not on any blocklists

What Are Some Ways You Can End Up On An Email Blacklist?

It can be extremely frustrating if you find yourself on a blocklist, especially if you aren’t doing anything wrong. It may take some time to repair your reputation, but there’s no need to rush out and get a new IP address. Some of the reasons you could find yourself on a blacklist include:

A Hacked Account

When a business’s email address ends up on a blocklist, it’s typically because a spammer hacked their account and sent out multiple malicious emails in the business’s name. In fact, a lot of times, you won’t notice that your account has been hacked until you run out of storage, a lot of your emails start bouncing, or one of your recipients reaches out to you about a weird email they got from “you.”

Or the business uses a shared IP, and someone else on the IP sent out a lot of spammy content. In the case of a shared IP, you may want to consider paying extra for a dedicated IP, so you don’t have to worry about other people’s Internet use.

You Had a Lot of Spam Complaints

One or two spam complaints won’t get you placed on a blocklist, but a plethora of spam complaints from your recipients or their ISPs will get you on a blocklist. To maintain your reputation, you want to stay out of spam folders as much as possible. Providing an unsubscribe link can give your recipients a way to stop receiving your emails without flagging your content as spam.

Your Mailing List is Outdated

If you have a list of recipients for your newsletters or email campaigns, you must ensure the list is updated constantly. Consistently sending out emails to inactive or fake email addresses, falling into spam traps, and continuing to send emails to people who unsubscribed from your content can land your IP address on a blocklist and decrease your engagement rates.

Your Inbox Isn’t Warm

You have to warm up your IP address to establish a relationship with ISPs, so they recognize your IP address as a trustworthy source of information. As much as you may want to start sending out as many emails as possible right away, it’s essential to ramp up your efforts steadily.

How To Avoid Being Added To An Email Blacklist

Here are some Dos and Don’ts for staying off of blocklists:



Update Your Email List Frequently

Buy Email Lists

Use Double Opt-in Methods

Use Spammy Words in Your Emails

Warm Up Your IP

Send Out too Many Emails

Authenticate Through SPF, DKIM, and DMARC

Hide Your Unsubscribe Link

Work to Improve Your Sender Reputation


How Many Email Blacklists Are There?

There are over 300 known email blacklists that anyone can access, and some have more pull than others when it comes to an IP determining whether or not to let your message through. Email blacklists are either IP Based: Real-time Blacklists (RBL) and Domain Name Server Black Lists (DNSBL); or Domain-Based: URI Real-time Black Lists (URL DNSBL).

There are four main types of email blacklists that affect email deliverability:

  1. New Domain Email Blacklists
  2. Spam Trap Email Blacklists
  3. Phishing/Ransomware Blacklists
  4. Spam Blacklist

And out of the 300 email blacklists out there, there are eight you want to stay off of:

  1. Composite Blocking List by Spamhaus
  2. Spamhaus Block List (SBL)
  3. XBL Exploits Block List
  4. SpamCop
  5. Passive Spam Block List (PSBL)
  6. Invaluement
  7. Barracuda Reputation Block List (BRBL)
  8. Sender Score

What To Do If You End Up On An Email Blacklist

If you’re taking as many preventative measures that you can, but you still find yourself on an email blacklist, the first thing to do is request to be removed from the list. Sometimes this is as easy as submitting a request to the list provider; other times, you’ll have to prove to the provider that you’re a legitimate company and you’re working toward creating a better reputation for your email address.

Blocklist operators may ask you to complete a couple of tasks or implement a new protocol before removing you from the list. For instance, they could require that you send your subscribers a re-permission request that allows them to indicate that they want to continue receiving mail from you. Or if you don’t have a double opt-in subscription policy, the blocklist operator may ask that you put one in place.

If there is no way to remove your address from the list and it’s affecting your deliverability, you may need to start over with a new IP address.  When setting up a new IP address, it’s essential to take steps to ensure that you don’t end up on a blocklist again.

Warmup Inbox can help you get your emails into your recipients’ inboxes and keep you off harmful blocklists. Get started for free.