Two middle-aged men look at a computer to find their email bounced and wonder how they could have avoided it from bouncing.

What Is A Bounced Email – And How to Avoid Email Bounces

Email is easy, personal, and fast – all it takes is writing a message and hitting Send. But not every email gets to where it needs to go. Here we look at how to deal with a bounced email and the steps you can take to avoid email bounces. 

Did you know that 88% of people use email every day? It’s one of the reasons that, for businesses, email is hard to beat. There’s also tremendous potential for profit. Email has the highest ROI, with $36 for every $1 spent, with some industries regularly exceeding $40.

young black man working on tablet and learning about marketing statistics

Email has almost limitless possibilities. It helps us establish valuable personal and professional connections. Businesses rely on email for just about anything:

  • Transactional messages like invoices or shipping alerts
  • Appointment reminders
  • Sales and marketing offers.

However, there is one prerequisite for any email to work: the message must reach the recipient. Unless it reaches the person on the other end, your email only represents wasted time and expense. Emails bouncing are antithetical to the channel’s purpose.

What is a bounced email? 

A bounced email is an email that does not reach its recipient. Typically, you get an automated message informing you that your email did not make it to the intended mailbox. 

While that’s discouraging, it has more profound implications when you send mass emails. Below we’ll explore the reasons why emails bounce – and what you can do to prevent it.

What does it mean when an email bounces? 

When you send an email and it gets rejected by the mail server, it has bounced. Think of it like trying to throw a basketball over a wall. If the ball got over, it would be received on the other end, which is your goal. If the wall blocks it, the ball bounces back to you. 

When an email bounces, you get an automated message known as a bounce message informing you that your email wasn’t delivered.

Screenshot of a bounce message indicating that the message wasn't delivered or bounced.
Here’s an example of a message you may receive if your email doesn’t reach its recipient.

Should I worry about bounces? 

For some, email bounces are little more than a nuisance. The problem is that getting bounces sends a message to internet service providers (ISPs) that you’re a likely spammer. Why? Because spammers tend to send their messages carelessly, which may result in bounces.

When you get bounces in excess of 2%, ISPs think you’re a spammer. This leads to a decrease in your sender reputation. Sender reputations are used by email service providers (ESPs) as a way to determine who is sending spam and who is legitimate. Just because you aren’t a spammer doesn’t mean you won’t be regarded as such.

Be diligent to avoid sending emails to an address that will bounce. Before you send an email, make sure you have a working email address. Not only do you want to reach the person in question, but anything more than two bounces/100 emails will hurt your sender reputation. You want your bounces to be as close to zero as possible.

Why do emails bounce?

There are so many reasons why your email bounced, and it can sometimes be challenging to find out exactly what happened.

Here are some of the prominent reasons.

The address is invalid

Either you or the person you’re trying to reach have made a typo, which means the email address is invalid. For example, when you captured someone’s address, you wrote instead of john@. Or maybe John himself gave you the wrong email. 

The mailbox is full 

If an email bounces because the mailbox is full, it’s probably because they haven’t deleted emails. Maybe they didn’t check their email for a long time and messages piled up. Their inbox is loaded with messages, and ran out of the allotted space. 

Screenshot of bounced email message indicating that the mailbox is full.
Your message will not go through if the recipient’s mailbox is full.

The message is too large

When the message is too large, it could be because you sent a large video file or tons of high-resolution pictures. The email you sent was too big for the inbox provider to accept.

You have a low sender reputation  

Your emails may bounce if you haven’t been following common sense email rules. The ISPs think of you as a spammer because you behave much as they do. For instance, you may be getting bounces because you don’t maintain your email list

The recipient does not exist 

You emailed dave@, but there is no Dave at that domain. That email will definitely bounce, unless the administrator has set up their domain as a catch-all. Catch-all domains accept all emails sent to a domain. Even then, having the wrong recipient could lead to a bounce.

Related: Learn more about catch-all emails

Screenshot indicating that email bounced due to the recipient not existing.
If you send an email to a non-existent recipient, there’s a good likelihood your email will bounce.

The domain name is invalid

If the domain name is wrong, your email has nowhere to go. Your mail server will send you a message that your email can’t be delivered. A wrong domain will always result in a delivery failure.

The recipient blocked your email

Sometimes, you’ll receive a message that your email was blocked, and other times it will simply bounce. If a recipient blocks you for any reason, there is a good likelihood that you will get a bounce.

You are on a blacklist

You can end up on a blacklist simply by emailing what are sometimes called honeypots. They’re email addresses that are designed to lure spammers. Even if you don’t send spam, but email one of these honeypots, you could be added to a blacklist which will lead to your emails bouncing. 

Related: How to run an email blacklist check

You have not implemented DMARC

Google and Yahoo’s updates on February 1, 2024 created new guidelines for anyone mass sending emails. DMARC stands for Domain-based Message Authentication, Reporting & Conformance. If you haven’t set up DMARC, you could get bounces or have your emails end up in the spam folder.

You encountered a DNS failure

A domain name system (DNS) failure can cause an email to bounce. Sometimes DNS servers will go offline. This can be the result of a malfunction at the data center. DNS issues are sometimes only temporary but nonetheless can cause a bounced email. 

You sent an email to a disposable email

Many people don’t want to give their real contact info. Instead, they use disposable or temporary emails, sometimes called burner emails

These emails “self-destruct” after a day or even hours. If you send a message to a disposable email, it will bounce back. It’s one reason why keeping disposable emails off of your list makes a lot of sense. If someone doesn’t care enough to give you their real email address, you won’t have meaningful exchanges or do good business.

Do bounced emails ever reach the recipient?

Getting a bounce means the email you intended to send did not reach the recipient. You should not consider the message or attachment you emailed to be in any way “delivered” if it bounced. 

However, there is a specific type of bounce that isn’t definitive – and that is a soft email bounce. Yes, there are two types of bounces:

  • hard bounces 
  • soft bounces

How are they different and what should you be aware of? Let’s find out.

What is a hard bounce in email?

A hard bounce is a permanent delivery failure, meaning your email will never reach the recipient. There are a few hard bounce reasons. It could be that the email address is invalid, mistyped, or currently nonexistent. 

A hard bounce indicates you should remove the email address from your contact list and not attempt to send any more emails to it.

Screenshot of hard bounce email message.
A hard bounce means the email you sent will never reach the intended recipient.

What is a soft bounce in email?

A soft bounce is a temporary delivery failure. This means the email has a chance of reaching the recipient in the future. Soft bounces frequently happen when the recipient’s mailbox is packed, their server is down, or when a spam filter blocks the email. 

In the case of soft bounces, your email service provider will continue to attempt delivery. If it doesn’t succeed within 72 hours, your message won’t make it to that mailbox.

Screenshot of soft bounce email message.
A soft bounce email means the email service provider will continue attempting the delivery of your message.

Related: Learn more about the difference between soft bounces and hard bounces

Why are my Gmail emails bouncing back?

Gmail is by far the most popular email service provider. Chances are you have lots of Gmail contacts in your database. And if you’ve noticed an unusually high Gmail bounce rate, you’re not alone. 

In an effort to keep security threats down – like phishing and spam– Google began mass-deleting inactive accounts. If you have many dormant subscribers in your list, their emails may be bouncing now due to Google’s initiative. 

Related: Learn  more about the Gmail purge here

Why are my Yahoo emails bouncing?

Before the Gmail purge, Yahoo had its own house cleaning. In 2019, the tech giant started deactivating and deleting inactive email accounts. For businesses storing and emailing old contacts, that resulted in massive bounce rates. 

ZeroBounce spoke with Marcel Becker of Yahoo, who commented that senders shouldn’t be holding on to dormant accounts in the first place. Removing them regularly prevents you from getting bounces. 

What can I do to prevent email bounces?

By now, you know bounces hurt your sender reputation and block your future campaigns and newsletters from landing in the inbox.

So, how can you prevent email bounces? The most reliable way is to check every email address before you reach out. Using an email bounce checker saves you a ton of time and gives you accurate results. 

There are two ways you can go about checking contacts to avoid bounced emails. 

Validate your entire email database

The easiest way to start improving the health of your email list is to run it through an email bounce checker or email validation service. Find a reputable platform, upload your entire list and begin the validation process.

Learn more about email verification.

An accurate email checker will identify any low-quality addresses which you should remove without delay. Consider making email validation a habit. On average, a quarter of your email contacts go bad every year. 

Validate emails in real time

Verifying your email list in bulk every quarter will help you avoid bounced emails. But if you want to go a step further, consider real-time email validation. With the help of an email validation API, you can be sure that every new contact you gather is real and valid. 

To check emails in real time, connect an API to every form where you collect email addresses. If your forms are unprotected, you’ll acquire poor-quality data. A real-time email validation API can stop bad contacts from infecting your list.

You can use a free email verifier

Website screenshot shows how an API can be connected at the point of entry. Image shows African American woman with green background.
An email validation API can stop invalid emails from getting on your list from the beginning.

Not everyone’s email list grows at the same rate. Whatever the purpose of your list, you can make an impact with even a few dozen subscribers. 

However, you should routinely check email addresses for freshness. If your email database is growing at a slower pace, consider using a free email verifier and check each contact before you add it to your list.

Not sure if your email list needs cleaning? Get a free evaluation

If you’ve never cleaned your list or don’t have any idea where to start, try a free email list evaluator. You can upload your list, and it will give you a free assessment and let you know what is lurking there. 

young man working on computer to evaluate his marketing list

Or maybe you were using a list and, for some reason, stopped emailing those people for a few months. Before you resume sending, get a thorough email list evaluation. Otherwise, you may get many bounced emails and jeopardize your future campaigns.

What you need to remember about email bounces 

If you’re just starting to learn about bounced emails and how to avoid them, this may have been a lot of information for you. To make things easier, here are the main points to remember:

  • Email bounces are delivery failures that occur when an email cannot reach the recipient’s inbox. 
  • There are two types of bounces: hard and soft. Hard bounces are permanent and result from invalid or non-existent email addresses. Soft bounces are temporary and result from issues at the recipient’s end, such as a full inbox, a server problem, or a content filter.
  • Bounces can harm your email marketing performance and reputation. They can lower your sender score and deliverability and affect your engagement and conversion rates. To avoid them, you must follow some best practices, such as using a reputable email service provider, regularly verifying your email list, segmenting your audience, and optimizing your email design and content.
  • You can never completely stop bounces, but you can (and should) prevent most of them.

We hope you found this article useful and informative. If you want to learn more about avoiding bounces, check out The Ultimate Guide to Email Hygiene and Scrubbing.