According to Statista, about 45% of all emails in 2023 were classified as spam—down from nearly 80% in 2011. This staggering volume is why email blocklists exist. These lists not only help reduce spam but also protect users from phishing attempts and malicious content. However, blocklists can occasionally affect legitimate senders due to common mistakes or misconfigurations.

What Is an Email Blocklist?

An email blocklist is a database of IP addresses or domains flagged for sending spam or suspicious content. Internet Service Providers (ISPs) and Email Service Providers (ESPs) use these lists to filter and block unwanted messages before they reach a user’s inbox.

Popular blocklist services include Spamhaus, Barracuda, and SORBS.

Why Do Emails or Domains Get Blocklisted?

Several factors can result in blocklisting:

• Spam complaints: Frequent reports from recipients flagging your emails as spam.
• Bulk emailing: Sending high volumes of emails without an established reputation or recipient consent.
• Suspicious content: Emails with misleading subject lines, excessive links, or spam-like language.
• Non-compliance: Violating regulations like CAN-SPAM or GDPR, or failing to include unsubscribe options.
• Poor IP reputation: Using an IP address previously associated with spam.
• Misconfigured settings: Incorrect authentication setups like SPF, DKIM, or DMARC.
• Compromised accounts: Hacked accounts that begin sending spam.

Being blocklisted impacts deliverability and damages trust. It’s crucial to follow best practices and maintain a healthy email-sending reputation.

How to Check if You’re Blocklisted

It’s a good habit to periodically check your domain or IP address for blocklisting. While tools like GlockApps offer paid options, free alternatives like MXToolBox and DNSChecker can help you verify your status.

Steps to Remove Your Email or Domain from a Blocklist

1. Identify the Issue
Use tools like MXToolBox to find which blocklist your domain is on. Visit that blocklist’s website to understand the specific reason behind the listing.

2. Fix the Root Cause
Once you identify the issue, take corrective action. You can resolve it internally or contact the support team of your email service provider for assistance.

3. Request Removal
After fixing the issue, submit a request for delisting through the blocklist’s official process. You’ll likely need to provide evidence of resolution and agree to adhere to email-sending best practices. Note: Some services offer help with this process for a fee.

How to Stay Off Email Blocklists

To maintain a strong sender reputation:

• Authenticate your emails: Set up SPF, DKIM, and DMARC to verify your identity.
• Use a clean list: Remove inactive or invalid addresses regularly to avoid high bounce rates.
• Always get consent: Send emails only to users who have opted in.
• Track performance: Monitor open rates, click-through rates, and spam reports for early warning signs.
• Choose a reliable ESP: Use platforms known for strong deliverability and compliance.
• Understand privacy laws: Follow regulations like CAN-SPAM and GDPR to avoid risky practices.
• Monitor your status: Use tools to regularly check your blocklist status and address issues quickly.

Final Thoughts

Avoiding email blocklists is essential for successful communication and maintaining your sender reputation. By practicing good email hygiene and monitoring your sending behavior, you can ensure your messages reach their intended audience without disruption.