1. Email Marketing

Everything you need to know about email blocklists

Have you ever wondered why some of your legitimate emails end up in the spam folder or never reach their destination? The culprit might be email blocklists. 

Email blocklists can have a significant impact on your email marketing campaigns and your overall sender reputation. In this blog post, we’ll discuss everything you need to know about email blocklists, including what they are, how they work, and how to avoid them.

What is an email blocklist?

An email blocklist is a list of IP addresses, domain names, or email addresses that have been flagged for sending spam or other unwanted content. Email service providers (ESPs) and internet service providers (ISPs) use these blocklists to filter out suspicious emails and protect their users from spam and malicious content.

If your email address or domain ends up on a blocklist, your emails may be blocked or marked as spam, making it difficult for your recipients to receive your messages.

How do email blocklists work?

Email blocklists are managed by various organisations. They collect data from different sources like spam traps, user reports, and email filters. When an IP address or domain has been flagged multiple times, it is added to the blocklist. ESPs and ISPs then use these blocklists as a reference to determine if an incoming email should be delivered, filtered as spam, or outright blocked.

Common reasons for getting listed

Several factors can lead to your email address or domain being blocklisted. Some common reasons include:

  • Sending emails to recipients who haven’t explicitly given you permission to contact them (see our GDPR guide for why this may also be illegal)
  • High complaint rates from recipients
  • A sudden spike in email sending volume
  • Poor list hygiene, such as sending to outdated or purchased email lists
  • Inadequate email authentication and security measures
  • Sending emails containing spammy content or malicious links

How to check if you’re on an email blocklist

There are several tools available that can help you check if your IP address or domain is listed on an email blocklist. Some popular options include:

By regularly monitoring your email sending reputation and blocklist status, you can identify potential issues and take corrective action promptly.

How to get removed from an email blocklist

If you find that your IP address or domain has been blocklisted, follow these steps to rectify the situation:

  1. Identify the reason for the blocklist: Review your email sending practices and identify any issues that may have led to your inclusion on the blocklist.
  2. Resolve the underlying issue: Fix the problems causing the blocklisting, such as improving your email list hygiene or implementing better authentication measures.
  3. Contact the blocklist provider: Most blocklist providers have a process in place for delisting requests. Follow their guidelines, provide evidence of the steps you’ve taken to resolve the issue, and request removal from the blocklist.
  4. Monitor your progress: Keep an eye on your email sending reputation and blocklist status to ensure that you remain off the list.

Tips for avoiding email blocklists

To minimise the risk of ending up on an email blocklist, consider the following best practices:

  • Always obtain permission from recipients before sending emails
  • Use double opt-in to confirm subscribers’ interest and intent
  • Regularly update and clean your email lists
  • Implement email authentication methods
  • Monitor your email sending reputation and deliverability metrics
  • Follow email marketing best practices and avoid spammy content


Understanding email blocklists and their impact on your email marketing is crucial for maintaining a healthy sender reputation and ensuring your messages reach your recipients’ inboxes.

Now that you’re equipped with the knowledge of email blocklists, you can take proactive steps to maintain a strong email sending reputation and avoid the dreaded spam folder. Keep your email lists clean, engage with your subscribers responsibly, and always prioritise delivering valuable content to your audience.

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