Email List Hygiene

Understanding Disposable Email Addresses—And What They Mean for Email Deliverability

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Maintaining a good sender reputation is difficult.  

So many factors contribute to how email providers perceive a sender.  

Factor in subscribers’ use of disposable email addresses, and now you must reevaluate how you handle list hygiene, measure engagement, and deal with the impact on your customer lifecycle.  

Let’s back up a little. What is a disposable email address?

A disposable email address is used to create a temporary account to avoid giving out a primary email address. 

Some mailbox providers make it easy to set up alias email addresses from your account settings, which allows you to filter emails by custom rules.  

Other providers exclusively create disposable addresses and automatically deactivate the account at a set expiration time. And of course, free email platforms allow subscribers to create as many accounts as they want. 

Why use a disposable email address? 

It’s easy to be suspicious of people who hide or lie about their identity–and there are certainly some bad actors out there who may be trying to sabotage your marketing efforts.  

But disposable and alias email addresses are widely used for a myriad of reasons, not all of which are intentionally deceptive.  

Some reasons are an understandable response to a company’s poor marketing practices—subscribers may have been burned before.  

Maybe they just wanted to watch a pre-recorded webinar and are now getting pestered with sales pitches because online content is gated and assumes an opt-in on emails.  

Or maybe they wanted an online coupon, but didn’t expect twice-daily emails.  

Almost everyone has wondered how they ended up on multiple unrelated companies’ lists at one point or another.  

Maybe they wanted to leave an anonymous comment or review on a company website, but the site requires that all commenters set up a profile with email addresses first.  

Another common reason for multiple alias addresses is to make it easier to create filtering rules for emails to be sent straight to designated folders. This is something email marketers do themselves for the purpose of testing their emails.  

However, one of the most popular reasons is to allow people to get multiple sign-up incentives (free trials, discounts, new member gifts, etc.). 

Types of disposable email addresses 

There are several types of disposable email addresses, each with different creation and deactivation methods. 

  • Throwaway accounts: These are one-time and/or limited-time use accounts before the address is deactivated. Setup is fast and easy, little to no private information is required, and deactivation is automatic. 
  • Forwarding account: Configured to automatically forward emails from this address to another address. This allows people to avoid giving out their personal addresses and to deactivate an alternate account. 
  • Alias: This type filters emails to a dedicated folder instead of the inbox. One appealing use for consumers is that it can help determine which companies may have sold your address to another company. If they begin seeing a flood of spam to their alias address, they can simply discard the alias.   
  • Private relay: Apple has an interesting variation on alias and forwarding accounts. If you “Sign in with Apple” to access third-party apps and websites, you can optionally elect to “Hide My Email”, which automatically creates an alternative address that forwards to your primary Apple ID email address. A decoy address can also be created manually in your Apple user profile. By switching off email forwarding, those senders using your private relay address will no longer be able to reach your inbox.  

Pitfalls of mailing to disposable email addresses 

Whether or not you agree with the reasons people sign up with disposable or alias addresses, they can have a negative impact on your email program.  

They will also generate little revenue, as this is not the behavior of loyal customers. When people create multiple aliases, they clutter your lists with duplicate members and bad data, adding to your efforts with low payoff.  

Throwaway emails allow a short window of time when the subscriber can receive emails. Once the address expires, subsequent emails will bounce. This can skew your audience metrics, shortening the average lifecycle length, and increase your subscriber churn and hard bounce rates.  

A high bounce rate (above two percent) can also damage your sender reputation, as it implies that you have poor list acquisition and hygiene practices. You can expect a hit to your inbox placement rate and possibly blocklistings if high bounce rates suddenly surge or become a longer trend. 

In the case of alias addresses, a rule may be set up to filter emails to a dedicated folder instead of the main Inbox, but your email service provider (ESP) will count it as “delivered.” 

There may be a delay between the time the email is received and the time it’s read since it’s not in the main inbox.  

In fact, those filtered emails may be ignored completely or deleted without reading when it’s time for housekeeping. This is why tracking engagement is essential. A list with a bunch of inactive subscribers is going to affect your reputation as well. In the eyes of mailbox providers, mailing to low-interest addresses equals spammer.  

If someone is using their alias addresses to sign up for multiple email lists, they are more likely to shut down the whole account, whereas with their primary account, they may properly unsubscribe instead when  receiving too many irrelevant emails.  

How to identify (and respond to!) disposable email addresses 

Because alias addresses can be set up as derivatives of a primary address, it may not always be easy to identify them. Validity BriteVerify and Everest List Validation tools will identify many disposable addresses, which will be marked as “Risky: Disposable.” However, addresses set up to forward to a primary address will not be detectable. 

With a throwaway account, the username is often a string of random letters, numbers, or words. The domain can either be the same domain for all users, or selected from a list of options. New disposable email providers pop up on the scene every day, so it’s impossible to list them all. That’s why List Validation is your best tool for identifying them. 

Alias addresses are often a variation on the main account. By adding period and/or plus symbols, filtering rules can be set up with the main account. Users may alternately use different versions of their names, like nicknames or initials. For example, [email protected] or [email protected].

You don’t necessarily need to remove these addresses, but keep track of their engagement just like you would any other subscriber. Remove if they do not respond to targeted winback and re-permissioning campaigns.  

Apple Private Relay addresses are sometimes recognizable, as they have a standard format for creating the accounts. The username is a string of random numbers and letters, but the domain will be “”

But other private alias addresses created by Apple have a slightly different format. The username combines unrelated words separated by periods with the domain “,” which is a domain that is also used in non-alias addresses, making it harder to determine if it’s an alias.  

How to prevent subscribers from using disposable addresses 

The overarching reason people use disposable addresses is due to lack of trust. New visitors have not established a relationship with you yet, so it’s your responsibility to be honest and upfront with your plans for their personal data.  

On every page with a sign-up form, whether it’s for downloading a guide, enrolling in your loyalty program, requesting contact, or posting to your community, include a link to your complete terms and conditions landing page. Additionally, summarize what you will and will not do with their personal information on the sign-up page.  

Do not assume consent for sending marketing emails just because someone signs up for a webinar, whitepaper, transactional email, or loyalty membership. Make that optional with a checkmark on the sign-up form. Briefly describe the frequency and types of emails they can expect if they do opt in to marketing emails.  

Instead of incentivizing subscriptions with immediate rewards (e.g., 20 percent off your first purchase), build return visits and loyalty through a tiered points system, in which rewards get better the more they spend.   

How to clean them from your lists 

It’s impossible to filter out all alias addresses, but you can ultimately treat the unidentified ones just like you’d handle any other subscriber: track engagement. Just like every other subscriber, if you find that they are ignoring your emails, you can use these tactics: 

  • Use double opt-in. Require subscription confirmation before adding new addresses to your marketing lists. This will at least eliminate people who give fake addresses or who don’t bother to check their email before their throwaway account expires.  
  • Require an email link click to redeem any sign-up rewards instead of including a discount code in the email. 
  • Practice list validation: Check for “Risky: Disposable” addresses by either uploading your marketing list of recent subscribers or set up the API to inspect the address at the point of sign-up.                                                                                                                                                                   
  • Instead of instant rewards, encourage new members to earn points that can be redeemed after reaching a defined level of spending. 
  • Winback campaign: Target inactive subscribers with an incentive to re-engage, such as a personalized offer. 
  • Re-permission: Those who don’t take the bait of your winback campaign can be sent a re-permission request. They can opt to stay on the list, adjust their subscription preferences, or unsubscribe. 
  • Sunset: After an extended time of zero engagement, it’s best to remove the address from your lists. You can always set a list rule to add them back if they use this address to engage again in the future (e.g., make an online purchase).  

The best defense against disposable email addresses 

Disposable email addresses may seem like a small percentage of your marketing lists, but they can do real damage to your sender reputation and marketing strategies.  

Get ahead of the problem by identifying and removing the obvious ones with the help of a tool like Everest List Validation. Tracking acquisition sources can also help you identify the biggest reasons people are using throwaway accounts.  

For more expert tips to maintain a clean email list, read our eBook, “Clueing in on List Hygiene.”