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Hard bounce vs. soft bounce: How to avoid these email delivery troublemakers

Reading Time: 6 minutes

Hard bounce, soft bounced emails, spam—these are keywords for poorly performed email campaigns. These troublemakers can spoil not only your email campaign results but your sender reputation as well, affecting future campaign deliverability.

Keep reading and learn how to distinguish hard bounce vs. soft bounce, correct issues you might have with your email delivery, and prevent your emails from bouncing in the first place.

What is an email bounce?

What does it mean when an email bounces? Put simply, an email bounce definition is when the recipient’s email server rejects your email message and the mail never arrives in its intended mailbox. It means that your message hasn’t been or can’t be delivered, and the email server sends it back to the sender.

The bounce rate indicates how healthy or stale your mailing list is. It has a significant impact on your sender reputation and is one of the most important email marketing metrics that you have to monitor your email marketing.

There are two different types of email bounce—a ‘soft’ bounce, and a more severe ‘hard’ bounce. Let’s look closer into the differences between them.

Soft bounce vs hard bounce in email marketing

What is a soft bounce?

A soft bounce is an email that hasn’t been delivered to your recipient because of temporary, fixable reasons that are often outside your own control. Soft bounces reasons include:

  • The size of the email is too large.
  • The recipient’s mailbox is full.
  • The email server is down.

There isn’t much you can do if the email server is down or if your recipient’s mailbox is full, however you have direct control over the size of your email. Pair down images, GIFs, and any dynamic media in order to create a lighter, more focused mail.

In these cases, email service providers resend the email. Omnisend tries to reach the recipient eight times over twelve hours, giving you time to address the problem. Most of the time, repeated and unresolved soft bounces are eventually converted by your email provider into a hard bounce.

So while a soft bounce is a problem that needs to be solved, it isn’t dangerous to your sender reputation until it becomes a hard bounce.


What is a hard bounce?

A hard bounce is an email that is sent back due to permanent, unresolvable reasons. While the causes of a hard bounce are varied, most of the time the recipient’s email address is invalid or no longer in use because:

The biggest, most important difference between soft vs hard email bounces is that a hard bounce can damage your deliverability rates and sender reputation, putting you at risk of being treated as a fraudulent email sender.

Having this status will spoil your email deliverability and is something to be avoided at all costs.

Learn more about email deliverability and sender’s reputation here: Improve Email Deliverability: Common Issues and Best Practices

How to improve your email bounce rate

While there isn’t any known way how to fix already bounced emails, the best thing you can do is effectively build your list following best practices, and maintain it with proper list hygiene.

This way, you can be sure that your contacts have given the proper consent, are interested in your brand, and are active subscribers. Prevention is the best medicine, so take steps to proactively prevent your emails from bouncing in the first place, or ending up in a spam folder.

That said, some emails can slip through the cracks, so let’s look at the reasons why hard bounces can occur.

The main reasons for hard bounces: How they affect deliverability

There are several common reasons for email hard bounces, and they affect deliverability in different ways. These include:

  1. As a sender, you use free email services like Gmail, Yahoo, or AOL. To reduce deceitful emails, many email service providers have changed their DMARC policies. According to this policy, your emails will not pass authentication and will be bounced. If you are an ecommerce business, you should use an email with your private business domain ([email protected]).
  2. Your list is out-of-date. If your mailing list was built several years ago, and you decided to use it only now, don’t be surprised by a high bounce rate. Your subscribers have probably changed their emails, forgotten about you, or are no longer interested in your content. In this case, you should delete users who have been inactive for months.
  3. You purchased or rented an email list. When you build an email list organically, you acquire subscribers who are interested in your brand. When you purchase or rent a list, you don’t. These lists often include old, inactive, and spam trap email addresses that cause high bounce rates and blacklisting. Never purchase or rent an email list!

    Omnisend’s Terms of Use do not allow you to use purchased or rented lists. If you use an email provider that allows these kinds of lists, you are putting your email program at risk.
  4. You suffer from typos. If your subscriber list is brand new but the bounce rate is high, the problem might lie in the way it was built. People tend to mistype their emails. So you can skim your contacts and check for simple mistypes like, @yahoo.con, etc. Use email verification to ensure email grammar and validation.

It’s also important to allow for an easy, hassle-free unsubscribe somewhere in your emails—it’s better to cut uninterested contacts loose rather than make them irritated enough to mark you as spam.

If your email goes to SPAM, find the reasons here.

What is an acceptable email bounce rate?

The number of bounced emails is directly related to the quality of your contacts list. A low bounce rate (up to 1%) indicates an engaged, well-maintained list populated with real and active subscribers who want to hear from you.

The industry standard for an acceptable bounce rate is less than 2%. If you start to go above that figure in your email campaigns, you should keep a close eye on things and make sure it doesn’t continue to climb. If your bounce rates get up over 5% then you might have a serious problem with your list that should be taken care of.

There are several ways to improve the hygiene of your email lists and get your bounce rate back down to an acceptable level. You can find out more about that here.

How to clean an email list and avoid a high bounce rate

If you notice an abnormally high bounce rate, it might be time for an old-fashioned email list cleaning. This is a relatively simple process, and should be done from time to time to maintain email list hygiene.

Start by segmenting out unengaged contacts from your list. These are contacts that haven’t interacted with your campaigns in quite some time. What you can do is send a re-engagement campaign, or a reactivation campaign. These will help you see which contacts you should remove completely. If they don’t respond or engage with the email, it’s time to remove them.

Whether or not the email is valid, you don’t want to send your campaigns to those who aren’t interested. They don’t want to receive them, and sending them anyway isn’t doing you or your sender reputation any favors.

You can also opt to use an email list cleaner to scrub your list for you. You upload your list to a list cleaning service, such as the one provided by Omnisend, which will validate email addresses and automatically remove any address that can’t receive an email.

List cleaning services may not catch all bad emails, but it’s a good preliminary step. You may have to segment out and remove bad email addresses after your next campaign once your list has been scrubbed.

Key takeaways

An up-to-date email list is crucial for your email marketing strategy.

High hard bounce rates have a significant negative impact on both the sender’s reputation and email deliverability rate. Using email marketing, you should strive to keep your bounce rate low, ideally under 2%—the lower it is, the better.

Email service providers, including Omnisend, help you to monitor the list’s status throughout email campaigns by measuring deliverability, bounce rates, and unsubscribes to give you a basic understanding of the welfare of your contact list.

It all begins with the health of your list, so make sure it is built with opt-ins and complies with the rules of your provider, as well as with relevant regulations like GDPR.

At the end of the day, use email best practices to build your list, let uninterested contacts freely unsubscribe to focus on quality, not quantity, regularly check and clean your list, and you won’t have any trouble!

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Article by
Karolina Petraškienė

Karolina is a writer, content marketer, and email enthusiast at Omnisend. When she's not curating articles, you can find her in the woods challenging herself in hiking boots or off-roading her bike.

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