What are temporary email service domains?

Temporary email service domains are domains used by services that provide disposable or burner email addresses. These addresses are designed for short-term use and often self-destruct after a specific period or a certain number of emails, making them unsuitable for long-term communication.

Why should I block disposable email addresses?

Blocking disposable email addresses helps maintain the quality of your email list, reduces spam registrations, prevents abuse of services (like repeated free trial sign-ups), and protects your sender reputation from being negatively impacted by high bounce rates or spam complaints.

How often do temporary email domain lists need to be updated?

These lists need to be updated constantly due to the dynamic nature of temporary email services. Providers frequently change or add new domains to bypass blocklists. Relying on outdated lists can lead to ineffective blocking.

Can using temporary email blocklists lead to false positives?

Yes, it is possible. Sometimes a legitimate domain might accidentally appear on a blocklist or be misidentified. This highlights the importance of using reputable sources and, if possible, combining multiple verification methods to minimize false positives.

How do I integrate a temporary email domain blocklist into my system?

You can integrate these lists by implementing real-time checks at points of entry, such as signup forms or checkout pages. This typically involves using an API provided by a commercial email validation service or developing a custom solution that queries a local or cloud-based blocklist (or blacklist) database.

Where can I find a list of temporary email service domains? - Technical - Email deliverability - Knowledge base

Finding a reliable, up-to-date list of temporary email service domains (also known as disposable or burner email addresses) is a common challenge for businesses and individuals focused on email security and deliverability. These services allow users to create temporary email addresses that often self-destruct after a short period, making them problematic for various reasons.

For companies, disposable email addresses pose significant risks, including spam registrations, abuse of free trials, and skewed analytics. For individuals, they might be a privacy tool, but for senders, they mean low engagement, high bounce rates, and potential damage to sender reputation. This ongoing battle to keep email lists clean and secure makes the search for effective blocklists (or blacklists) an essential task.

Why blocking temporary email addresses is crucial for businesses

Disposable email addresses (DEAs) pose significant challenges for businesses. They are often used to bypass registration requirements, access free trials repeatedly, or engage in malicious activities such as spamming, phishing, or creating fake accounts.

Allowing DEAs to register on your platform or subscribe to your mailing lists can lead to inflated user counts, reduced engagement rates, and a degraded sender reputation. When email service providers (ESPs) see a high volume of emails sent to these temporary addresses, it signals poor list hygiene and can result in your legitimate emails landing in the spam folder or even your domain being added to an email blocklist (or blacklist).

By proactively identifying and blocking these domains, you can ensure that your user base consists of genuine, engaged individuals. This not only improves the accuracy of your analytics but also significantly enhances your email deliverability rates, as you're sending to valid and responsive recipients. This is critical for maintaining a healthy sender reputation.

Where to find lists of temporary email service domains

The quest for a comprehensive list of temporary email service domains is an ongoing challenge because these services frequently rotate their domains to avoid detection. However, there are several valuable sources where you can begin your search, each with its own advantages and considerations.

One common starting point is public GitHub repositories. Projects like disposable-email-domains/disposable-email-domains offer extensive lists of known temporary and disposable email domains. While these lists are often community-maintained and readily accessible, their completeness can vary, and they may not always be up-to-date with the latest domain rotations. You can explore some of these lists on GitHub to get a foundational dataset of domains. For more options, see where to find comprehensive lists.

Beyond open-source lists, several specialized services maintain dynamic, real-time databases of temporary email domains. These services often leverage advanced detection methods and constant monitoring to provide more current and accurate data. They typically offer APIs for automated integration, which can be invaluable for businesses needing to implement real-time email validation at points of entry, such as signup forms. Examples of temporary email services that you'd want to block include Mailinator, YOPmail, and Temp Mail. These are well-known for providing burner email addresses.

Accessibility and cost

These lists are generally free and publicly available, often found on platforms like GitHub. They are great for initial research or smaller projects.

Data freshness

Updates rely on community contributions, which can be inconsistent. There's a risk of lists becoming outdated quickly, leading to missed temporary domains or false negatives.

Real-time accuracy

Providers dedicate resources to continuously monitor and update their databases, offering more current and comprehensive coverage of disposable domains. Many provide APIs.

Integration and support

Typically offer robust APIs for seamless integration into existing systems. Some also provide support and additional email validation features.

The dynamic nature of temporary email domains and blocklist maintenance

One of the biggest hurdles in dealing with temporary email domains is their constantly evolving nature. As soon as a domain gains notoriety and is added to widely used blocklists (or blacklists), these services often register new domains to circumvent detection. This rapid rotation means that any static list, no matter how comprehensive initially, will inevitably become outdated over time.

Effective management of a temporary email blocklist requires continuous effort. It is not a one-time setup, but rather an ongoing process of monitoring, updating, and adapting. Relying solely on historical data can lead to legitimate emails being sent to disposable addresses, harming your sender reputation, or conversely, blocking valid users who happen to use a newly added domain that is not truly temporary.

Businesses should consider a multi-faceted approach, combining publicly available lists with dynamic, real-time verification mechanisms. This hybrid strategy helps to mitigate the risks associated with static lists while providing a more robust defense against temporary email usage. It is also vital to understand the difference between a blacklist and a blocklist and how each impacts your email strategy.

Constant vigilance required

The fight against temporary email domains is an ongoing battle. Domains are frequently rotated to bypass detection, making static lists quickly obsolete. Your blocklist (or blacklist) needs continuous updates.

Combining resources

Don't rely on just one source. Integrate data from multiple reputable GitHub lists and consider commercial APIs for real-time validation to catch newly emerging domains.

Reputation protection

Failing to block temporary domains can negatively impact your sender reputation, leading to lower inbox placement rates. Maintaining a clean list is crucial for long-term email deliverability.

Strategies for implementing and leveraging temporary domain lists

Once you have access to lists of temporary email service domains, the next step is to integrate them effectively into your email infrastructure and user acquisition processes. The goal is to prevent these addresses from ever entering your system, thereby protecting your email list quality and sender reputation.

For example, at the point of user registration or newsletter subscription, you can implement checks against your chosen blocklist (or blacklist) of temporary domains. If an entered email address matches a domain on your list, you can immediately prevent the registration or subscription. This proactive approach saves you from sending emails to addresses that are likely to bounce or be marked as spam. For more technical guidance, you can explore strategies for blocking disposable email domains.

For existing email lists, periodic cleaning and verification are essential. While real-time checks prevent new additions, existing temporary email addresses may still reside in your database. Regularly verifying your email list helps identify and remove these problematic addresses, further improving your overall email deliverability. Understanding how to identify suspicious email domains and spam trap networks is also key.

Basic check for a disposable email domainJavaScript

const disposableDomains = [
  "mailinator.com",
  "yopmail.com",
  "temp-mail.org",
  // ... many more domains
];

function isDisposableEmail(email) {
  const domain = email.split('@')[1];
  return disposableDomains.includes(domain);
}

Views from the trenches

Best practices

Regularly audit and update your disposable domain blocklist to keep it effective against new domains.

Combine open-source lists with commercial verification services for a more robust defense against temporary emails.

Implement real-time checks at signup and lead generation points to prevent disposable email addresses from entering your system.

Educate your team on the importance of maintaining a clean email list and the risks posed by temporary email addresses.

Common pitfalls

Relying solely on static, outdated lists of disposable email domains that quickly become ineffective.

Not integrating domain blocking mechanisms at key entry points, allowing bad data to infiltrate your database.

Overlooking the need for continuous monitoring and updating of your blocklist, leading to reduced deliverability.

Aggressively blocking domains without proper verification, potentially leading to false positives and blocking legitimate users.

Expert tips

Focus on the MX records of suspicious domains, as temporary email services often re-use the same mail servers even with new domains.

Develop a process for regularly reviewing bounce reports and engagement metrics to identify potential new temporary email domains.

Consider implementing email authentication protocols like DMARC, SPF, and DKIM to improve overall email security and deliverability, complementing your blocklist efforts.

Use an email validation API that specifically includes a disposable email detection feature for automated real-time checking.

Marketer view

Marketer from Email Geeks says that there are several lists available on GitHub, but their completeness and criteria for listing can vary, so it is important to review them.

October 1, 2022 - Email Geeks

Marketer view

Marketer from Email Geeks says that many domains on GitHub lists might be dead or lack MX records, which reduces their immediate utility.

October 2, 2022 - Email Geeks

Maintaining a clean email ecosystem

Finding and maintaining a current list of temporary email service domains is a critical, ongoing task for anyone serious about email deliverability and data quality. These domains are a moving target, constantly evolving to bypass detection. For more details on what happens when your email address ends up on a blacklist, this guide is useful.

While open-source GitHub repositories provide valuable starting points, a truly effective strategy often involves combining these resources with the real-time accuracy offered by commercial email validation services. Proactive blocking at entry points and regular list hygiene are paramount to protecting your sender reputation and ensuring your messages reach legitimate inboxes.