What are disposable email addresses and why are they a concern?

A disposable email address (DEA) is a temporary email account, often expiring quickly, used to avoid spam or protect privacy. For businesses, DEAs lead to inflated lists, high bounce rates, skewed analytics, and ultimately, poor email deliverability .

Are there any downsides to blocking all disposable email addresses?

While blocking DEAs improves list quality and deliverability, it might also deter some users who are genuinely interested but initially hesitant. A balanced approach could involve soft blocking for marketing emails while allowing transactional communications.

How can I effectively identify and prevent disposable email sign-ups?

You can use email validation services , maintain an updated blacklist of DEA domains, and implement reCAPTCHA or other bot-prevention measures at sign-up. Regular list cleaning is also essential.

What if I don't want to block DEAs entirely but still improve engagement?

If a user signs up with a DEA, engage them with valuable content and incentives (like exclusive offers) to encourage them to switch to a permanent email address. This could convert a temporary lead into a loyal customer.

My emails to new sign-ups are hard bouncing, why?

A common cause is a high volume of sign-ups from disposable domains, leading to immediate non-existent address bounces. Regularly validating your list and removing unengaged subscribers can help prevent this.

Should I block disposable email addresses from my email list? - Sender reputation - Email deliverability - Knowledge base

Disposable email addresses (DEAs), sometimes called temporary, throwaway, or burner emails, offer users a way to sign up for services without using their primary email. This can seem appealing from a user privacy perspective, but for businesses, it introduces a complex question: should you block these email addresses from your mailing lists? It's a question many of us in the email deliverability space grapple with regularly, and the answer isn't always straightforward.

The primary intent behind using a DEA is often to maintain privacy and avoid spam in a main inbox. Users might use them for one-off registrations, accessing free trials, or downloading content without committing to an ongoing relationship. While the intention might be innocent, the impact on your email program can be significant. I've seen situations where a sudden influx of sign-ups from domains like sute.jp has led to a spike in hard bounces, raising immediate red flags about list quality.

This article will explore the implications of disposable email addresses on your email program, weigh the arguments for and against blocking them, and offer practical strategies for managing them effectively. My goal is to help you make an informed decision that supports your deliverability and overall business objectives.

Understanding disposable email addresses

A disposable email address is designed for short-term use, typically expiring after a set period, like 10 minutes or 24 hours, or after receiving a certain number of messages. Services providing these emails, such as Temp Mail or 10MinuteMail, are popular because they require no registration, offering instant, temporary inboxes. This appeals to users who want to avoid their primary inbox being cluttered with promotional emails or who are concerned about data privacy.

From a user's perspective, using a disposable email address is a quick way to bypass certain requirements or access content without providing a long-term commitment. For instance, they might use one to grab a discount code, download an ebook, or try out a service's free tier. While some disposable mailboxes do indeed receive and allow users to open emails for a temporary period, many are quickly abandoned or expire, rendering them useless for ongoing communication.

It’s important to understand the motivation behind their use. Often, it's not malicious, but rather a desire for convenience or a way to test out a service anonymously. However, this doesn't diminish the negative impact they can have on your email program, which is why considering a blocklist (or blacklist) strategy becomes necessary for many businesses.

The impact on email deliverability and data quality

Allowing disposable email addresses onto your list can significantly hurt your email deliverability and overall marketing efforts. The most immediate impact is often an increase in hard bounces. Many DEAs are designed to expire quickly, meaning subsequent sends to those addresses will result in permanent failures. High bounce rates signal to mailbox providers like

Google and

Yahoo that your list quality is poor, which can negatively impact your sender reputation.

Beyond bounces, DEAs can distort your engagement metrics. If subscribers use a temporary email to access an immediate benefit and then abandon it, your open rates and click-through rates for subsequent emails will suffer. This artificially low engagement tells mailbox providers that your content isn't relevant to recipients, potentially leading to your emails being flagged as spam or directed to the junk folder. This is why poor email deliverability often stems from list hygiene issues.

Furthermore, allowing DEAs can lead to inflated list sizes, higher costs for your email service provider (as you're paying to send to non-engaging or invalid addresses), and a general degradation of your customer data. It becomes harder to accurately segment your audience, personalize communications, or build lasting customer relationships when a significant portion of your list is made up of transient contacts. Effectively, you're investing resources into contacts who aren't interested in an ongoing engagement.

To block or not to block: a strategic dilemma

Given the downsides, the argument for blocking disposable email addresses outright is strong. Preventing them from entering your list in the first place saves you from future deliverability headaches and ensures a cleaner, more engaged audience. However, there's also a nuanced perspective to consider, especially if your business model occasionally caters to users seeking quick access or anonymity.

Arguments for blocking DEAs

Improved sender reputation: Reduces hard bounces and complaints, signaling to mailbox providers that you maintain a high-quality list. This helps prevent your domain from being placed on an email blocklist (or blacklist).
Accurate metrics: You get a clearer picture of your campaign performance with reliable open and click-through rates.
Reduced costs: Avoids paying your ESP for sending emails to addresses that will never engage.
Better engagement: Focus your efforts on genuinely interested subscribers, fostering stronger relationships.

Arguments against strict blocking

Potential customer loss: Some users might genuinely be interested but prefer a DEA for initial caution or to test your service privately. Blocking them might prevent a future loyal customer.
User experience: A strict block can frustrate users who are trying to sign up legitimately but prefer anonymity.
False positives: While rare, some legitimate, lesser-known domains might be mistakenly identified as disposable and blocked.

One approach for those who are hesitant to block all DEAs is to implement a verification process or a tiered approach. You could allow transactional emails to these addresses initially, but require a more permanent email for access to premium content or services. This incentivizes users to provide a long-term contact method while still allowing them to explore your offerings.

Implementing a blocking strategy

If you decide that blocking disposable email addresses is the right strategy for your business, the key is to implement it effectively. The most common method involves maintaining a list of known disposable email domains and preventing sign-ups from those domains. These lists are regularly updated to keep pace with new DEA services. You can also integrate with email verification services that flag DEAs in real-time.

For instance, at the point of sign-up, your system can check the entered email address against a blacklist of known disposable domains. If a match is found, the user can be prompted to provide a different email address. This prevents the transient addresses from ever reaching your valuable subscriber list, which is crucial for maintaining email list hygiene.

Example: Basic disposable email domain checkjavascript

function isDisposableEmail(email) {
    const disposableDomains = ['temp-mail.org', '10minutemail.com', 'mailinator.com', 'sute.jp'];
    const domain = email.split('@')[1];
    return disposableDomains.includes(domain);
}

// Example usage:
const email1 = "test@temp-mail.org";
const email2 = "user@example.com";

console.log(isDisposableEmail(email1)); // true
console.log(isDisposableEmail(email2)); // false

Automated solutions can significantly streamline this process. Many email verification services offer real-time checks that not only identify disposable emails but also flag other risky addresses, such as spam traps and invalid addresses. Incorporating such a tool can be a powerful way to prevent bot sign-ups and suspicious contacts from polluting your list.

Key considerations for managing DEAs

Regular list cleaning: Even if you block new sign-ups, regularly audit and remove any existing disposable email addresses from your list. This ensures you're sending only to valid, engaged contacts.
User incentives: Consider if offering a compelling incentive could encourage users to sign up with their primary email addresses instead of disposable ones.
Transactional vs. marketing: Differentiate between essential transactional emails (e.g., password resets) and marketing emails. You might consider allowing transactional emails to DEAs while blocking marketing communications.

Making the right decision for your email program

Ultimately, the decision to block disposable email addresses from your email list should align with your overall business goals and email strategy. For most businesses focused on building long-term customer relationships and maintaining strong deliverability, a proactive blocking strategy is highly beneficial. It ensures that your valuable email list is populated with engaged subscribers who are genuinely interested in receiving your communications.

While there's a minor risk of alienating a very small segment of users, the benefits of cleaner data, improved sender reputation, and more accurate analytics far outweigh this concern. Regularly reviewing your email list for invalid or transient addresses, regardless of your blocking policy, remains a best practice for optimal email performance.

By actively managing disposable emails, you invest in the long-term health and effectiveness of your email marketing program, ensuring your messages reach the inboxes of those who truly want to hear from you.

Views from the trenches

Best practices

Always validate email addresses at the point of sign-up to catch DEAs early.

Regularly segment your list to identify and suppress unengaged subscribers, including those with DEAs.

Consider a double opt-in process to confirm subscriber intent and filter out temporary emails.

Integrate an email verification API that specifically detects and flags disposable email domains.

Common pitfalls

Relying solely on manually updated blacklists, as new DEA domains emerge constantly.

Not differentiating between transactional and marketing emails when blocking DEAs.

Failing to monitor hard bounce rates, which can indicate an influx of disposable addresses.

Ignoring the user experience ramifications of overly aggressive blocking measures.

Expert tips

Use email verification services to catch DEAs and other risky addresses in real-time.

Analyze the lifetime value of users who initially sign up with DEAs before making a blanket blocking decision.

Maintain a dynamic list of disposable email domains, updated frequently, for your blocking strategy.

Implement a grace period for new subscribers, observing their engagement before determining whether to block.

Marketer view

Marketer from Email Geeks says that some disposable mailboxes do open emails, but their purpose is usually single-use, making them mostly useless for ongoing subscriber engagement. However, transactional communications should not be excluded.

2021-05-11 - Email Geeks

Marketer view

Marketer from Email Geeks says they noticed an abundance of disposable email addresses due to a bunch of hard bounces, indicating an issue with list quality.

2021-05-11 - Email Geeks