(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 a Blacklist?
An email blacklist is a reference for ISPs to determine how safe it is to accept messages coming from various domains and addresses. These lists are online collections of email addresses and domains that recipients have reported to be sending out spam or malicious content on multiple occasions or users who have a bad sender reputation.
Getting placed on a blocklist can be incredibly frustrating, to say the least, because it stops your email marketing campaigns in their tracks. You could be making serious strides with a customer and then suddenly be unable to send a single message. It’s essential to keep in mind that blocklists are made to keep consumers safe from unwanted content, and the blocklists protect your inbox too.
Blocklists work through tracing IP addresses that are attached to the sender’s emails. ISPs can trace the sender’s location through the IP address and identify the sender of a message. Once they know who’s sending the message, they can evaluate whether the message is safe or not.
When an ISP is determining the safety of an email, blacklists provide the first line of defense between the content of the message and the recipient. These lists aren’t the only thing that determines email deliverability, but being placed on a blocklist can have more immediate and strict consequences than other deliverability factors.
How to Remove Your Email from a Blacklist
Getting off of a blacklist will vary depending on which list you’re on. As soon as you identify which list you’re on, it’s best to contact the list administrator to figure out the next steps.
Here are some common lists and how to get off of them:
- SORBS: create a SORBS account and request delisting
- Trend Micro: request delisting
- Barracuda: look up your reputation and request delisting
- DroneBL: look up your reputation and request delisting
- WPBL: request delisting
- SpamRats: request delisting on all four lists: RATS-Dyna, RATS-noPtr, RATS-Spam, RATS-Auth
- 0Spam: remove hacker or spoofer, create an 0spam account, and request delisting
- MIPSPace: request delisting
- SpamCop: you’ll automatically be delisted after 24 hours without a spam report
- Spamhaus: request delisting
- Suomispam: request delisting
- Microsoft: secure your web server, get your IP address off of all blocklists, set an SPF record, set up a PTR record, verify your mail server setup, and request delisting
- Google: review the Bulk Sender Guidelinesand complete the Bulk Sender Contact Form
How Did My Email End Up on a Blacklist?
As more people began to communicate through emails, cybercrime became more prevalent. There have been multiple efforts to regulate spam and malicious emails, from the CAN-SPAM Act to more sophisticated spam filters. And, of course, more sensitive blocklists.
There are multiple reasons you could be placed on a blocklist, including:
- Someone Hacked Your Account, or You’re on a Shared IP – The most common ways to end up on a blocklist are also the most frustrating because they aren’t your fault. If someone hacks your account or spoofs your emails, then you can get blamed for sending out spam. Or, if you use a shared IP instead of a dedicated IP, ISPs may place the shared IP on a blocklist if one user abuses their privileges.
- You Haven’t Updated Your Mailing List – It’s crucial to constantly update your mailing list to weed out old or inactive email addresses. As soon as an email bounces or someone requests to be removed from your list, it’s your responsibility to take them off ASAP. Stay away from people who sell email lists because the lists are likely filled with fake, old, or spam trap email addresses. While it takes more time to generate leads organically, it’ll be better for you in the long run to take your time.
- You’ve Had Multiple Spam Complaints – Ideally, you want your emails going into your recipients’ inbox for a lot of reasons. But the more your content is flagged as spam by the user or the ISP, the more likely it is that you’ll end up on a blocklist.
- Your IP Address Wasn’t Warm Enough for the Volume of Sent Emails – If you don’t warm up your IP address, then ISPs may think you’re a spammer and place you on a blocklist. Slowly work your way up to sending the number of emails you want to send in a day, so ISPs have a chance to recognize your address as a reliable sender.
How to Identify an Email Blacklist
There are over 300 public blacklists online, and there are eight you definitely want to stay off of:
- Composite Blocking List by Spamhaus
- Spamhaus Block List (SBL)
- XBL Exploits Block List
- Passive Spam Block List (PSBL)
- Barracuda Reputation Block List (BRBL)
- Sender Score
While 300+ blocklists are daunting, there are multiple tools you can use to ensure you’re staying off of the extremely detrimental lists:
- 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
How to Avoid Getting Blacklisted Again
There are three easy steps you can take as you move forward from being on a blocklist:
1. Keep Your Email List Up to Date
Just like it’s important to clean out your closet every now and then, it’s essential to tidy up your email list all the time. Ways to keep your mailing list clean include:
- Removing emails from your list the first time they bounce. Multiple bounced emails can get you but on a blocklist.
- Giving customers the chance to unsubscribe from your emails. This allows them to remove their name from your list without reporting you as spam. Additionally, honor their request to unsubscribe as quickly as possible, so you aren’t flagged as spam by their ISP.
- Not buying email lists to generate leads. These lists are often filled with fake emails or spam traps and can only hurt your sender's reputation.
2. Have Subscribers Double Opt-In for Emails
Single opt-in practices only require customers to check a box or leave a box unchecked in order to start receiving emails from a company. This can lead to frustrated customers who didn’t realize they signed up for emails and—you guessed it—spam complaints. Using double opt-in not only allows your customers to verify that they want to receive email content from you, but it also gives them the opportunity to ensure their email was entered correctly.
3. Warm Up Your IP and Keep It Warm
Taking the time to warm up your IP address enables ISPs to get comfortable with your emails. By steadily increasing the number of emails you send, your recipients’ ISPs will recognize you as a reliable sender, and your messages will go straight to your recipient’s inbox.
Slowly increase the number of emails you send each day until you reach your target volume by segmenting your email list. As you warm up your inbox, you’ll build up a positive sender reputation. Another way to boost your reputation while warming up your inbox is to have back and forth conversations with another email account, whether it’s a customer or your co-worker Steve.
Warmup Inbox can help you get your emails into your recipients’ inboxes and keep you off harmful blocklists. Get started for free.
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