What is a Disposable Email Address? A Guide to Blocking Fake Users

These are temporary email accounts used for the sole purpose of registering and verifying something. Such email accounts can self-destruct just a few minutes after they are created.

In this guide, we'll break down how disposable emails operate, the negative impacts on your business, and how to best identify and stop disposable email addresses. These measures will protect your business from the problems associated with fake accounts, and save time and money.

Before you work on stopping fake users, it helps to understand how throwaway accounts actually work. This section attempts to explain, at a basic level, what a throwaway email account is, what throwaway accounts are, and what types of throwaway accounts you may encounter.

Understanding the Terms

First, let's get an understanding of the distinction between regular emails and throwaway emails. A regular email alias is something like yourname+sale@gmail.com. Even though the address is slightly different, it still delivers messages to the same inbox. With a DEA provider (Disposable Email Address provider), you do get an email, but it's disposable and only valid for a certain period of time. There is no need for a password, and the inbox is often public. Emails to the address either disappear or bounce back after a certain period of time.

These disposable emails are used only once and afterwards forgotten. The email is copied, pasted into your sign-up form, and the user clicks the verification link. After that, they never bother to check that inbox. In other words, the user gets what they need — a quick verification email — by getting around your security measures.

Types of Disposable Email Provider Services

Not all disposable email provider services for throwaway emails work in the same way. In practice, there are two main categories, and understanding the difference is important for keeping fake users out.

Dedicated Services

Some services exist specifically to generate disposable inboxes. Masquerading as privacy tools, they allow you to access temporary email addresses to sign up for a number of websites. Guerrilla Mail and Temp Mail are two such examples. People use these to protect their identity. But because these tools are so easy to use, they have become a common source of fake accounts.

Genuine Data Protection

Of course, not every masked email is malicious by default. Apple provides features like "Hide My Email," and services like Proton Mail and Firefox Relay keep users safe from being tracked. Some users simply care about privacy — fair enough. Now, your challenge is that, from your system's point of view, it's not always easy to tell the difference between someone protecting their privacy and someone trying to get around your signup rules.

User Experience

From the user's perspective, creating a fake account with a disposable email is surprisingly easy. The user first goes to a site that provides them with the ability to create a temporary email address. Then, they simply paste the temporary email into the designated field to create an account.

Next, they look for the verification email on the same site and use it to complete your checks. They can access your platform within minutes. After that, they leave and never look at that email again. They become almost invisible and unreliable to you.

Fake users drive up the number of registered users on your site, but the problem is more severe than that for your business. They can cost you money and generate bad data that can legitimately harm your business — here is how.

Promotional Abuse and Freemium Abuse

Many businesses offer new users promotions or free trials; it's a very common marketing technique. However, one downside is free trial abusers. Such users can get multiple free trials, coupons, and so on by signing up with fake or disposable emails.

Free trials are one of the most common marketing techniques — they have been shown to be very powerful ways to showcase your product and attract users. However, free trial abusers are the major downside of this method — they can create multiple sub-accounts and, for example, get multiple promotional codes without ever converting to a real user.

When new accounts are being created by a small group of users using fake or temporary email addresses, all of the costs associated with those accounts can really add up, including server storage, customer support, sales support, and customer service. According to some estimates, if not managed properly, up to 40% of new accounts could be fake. This can be avoided by using a temporary email address checker.

Marketing Waste and Bounce Rates

A CRM full of disposable emails gives you no reason to think that you've spent your marketing money wisely. You could send out emails to customers informing them about how to use a product or providing them with discount offers, but if no one sees them, your time has also been spent completing useless tasks.

When your email is sent, it goes to the recipient's inbox — but a temporary email address is nowhere to be found. If too many of your sent emails hit invalid addresses, most email service providers will start identifying your emails as spam and, subsequently, prevent your legitimate marketing emails from being delivered in the future. You can avoid this by using a spam email checker before adding a new entry to your email list.

Security and Infrastructure Vulnerabilities

The potential losses from sales and marketing are bad, but there is an even larger risk — losses from bot attacks that may use disposable email addresses to create large numbers of fake accounts. The result is that your website may get thousands of "new users" in a very short time, and your internal registration-protected infrastructure suddenly gets exposed. Bots can cause problems such as overloading your servers, stealing data, and breaking your systems.

The Analytics Nightmare

Daily and monthly active users (DAU and MAU) are often used to analyze a company's growth. If there are a large number of artificial sign-ups, these metrics become totally unreliable. With distorted data, a company will address issues that do not exist.

The obvious question is — how do you detect disposable accounts? Luckily, there are several ways to identify them.

Disposable Email Checker

A disposable email checker is much better for more precise control. This checker maintains a list of all the disposable email domains that it tracks. When someone signs up, the checker tries to find the domain on its list. If the domain corresponds to a service that offers temporary email, it will reject the sign-up. With the disposable email checker, new temp-email domains are added regularly and unknown domains are blocked.

MX Record and SMTP Handshakes

A legitimate email domain has an active MX record to indicate where email should go. If there's no MX record or it's broken, there is a chance the email address is not valid. The next check involves using an SMTP handshake to communicate with the mail server and check for an appropriate response. An unusual response indicates the email address is likely not valid. Disposable emails might have valid MX records and respond normally on an SMTP handshake.

If you're dealing with lots of signups, manual checks aren't really practical. What you need is a method that's smart enough to distinguish real from fake users, and a temporary email API is perfect for this.

Automation

With an API, your system communicates with the disposable email checker automatically, and that only takes seconds.

A user enters an email into your sign-up form, you send it to a temp email API, and await an "allow" or "block" response. If "block" is returned, you let the user know they need a valid email to sign up. This way, you avoid having to manually review and clear the email. And more importantly, your system stays protected.

Advantages of Instant Processing

Temporary email APIs are useful and they work instantly.

You can prompt users to sign up with a real email. This means you are preventing fake users from entering your system and keeping your email lists clean. You are saving support resources from being wasted on fake users, your emails are reaching real users, your lists are clean, and your efforts are focused on real users instead of being wasted on fake sign-ups.

Even with detection tools in place, additional safeguards can further strengthen your defenses. Let's get into it.

Don't Just Block, Verify

First, you have to remember that not every suspicious sign-up is malicious. Some users may seem suspicious but might be real users who simply care about privacy and want to avoid sharing their primary inbox. So, instead of blocking every single email that seems suspicious, you can ask them to prove their identity in another way.

For example, you can ask users to confirm their identity via phone call or social media. This type of two-factor verification allows real users to get through while blocking most of the fakes. This way, you help make the experience fair for all of your legitimate users.

Monitoring and Adapting

Every day, scammers are coming up with new and better ways to get past your defenses. This is why you must periodically review the logs of your disposable email checker.

Check the blocked domains and look for new ones that you haven't yet blocked. If you are proactive and stay on top of things, you will always have a good sense of what you are up against, even when scammers come up with new tricks.

IP-Based Blocking

Bots and fake sign-ups can often come from the same IP address ranges. If you collect the IP addresses of flagged or suspicious sign-ups, you can quickly block many fake users in the future.

When you use an IP blocking tool along with your temporary email API, achieving an even stronger barrier against fake accounts becomes possible. A decreased number of sign-ups from bad accounts will make your platform safer for all users.