Doesn’t it sound like a nightmare to have your emails bounce?

For an email marketer, there is nothing worse than bounced emails.

Because bounced emails inflict your sender reputation and email deliverability.

With every mail that bounces, you are bleeding out a valid recipient’s mail server.

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Truth is… email bounces happen to everyone, they are a common part of email marketing.

People change their email addresses without notifying the mailing lists they’re on, their accounts remain inactive for years before they get disabled.

It’s important to understand hard bounces and why they happen.

In this article, we talk about What is a bounce-back email? What causes an email to bounce back? Types of hard bounces? And How can you reduce your bounce-back rate?

Keep on reading!

What is Email Bounce Back?

Email bounce back is when an email you send inability to get delivered to your recipient’s mailbox due because of a certain issue.

Email bounce back happens when you send an email and it gets rejected from the recipient’s side.

This is what is called a bounced email.

There are other causes for servers to reject emails, all going back to invalid emails, and inactive email addresses.

The amount of bounced emails per number of sent emails is what is called a bounce rate.

An on-growing high bounce rate can have a negative impact on your email marketing, sender reputation, and campaign outreach.

A sender reputation is a score that internet service providers (ISP) assign to an email sending IP address.

Your sender score is what determines if your email will bounce back or end up in spam.

In fact, many email service providers (ESP) like Gmail and Outlook can penalize a sender’s reputation if the bounce rate is over 5%.

As a general rule of thumb, you have to maintain a bounce rate below 3%.

This can be achieved by following ethical called “white-hat” tactics.

Why Are Your Emails Bouncing Back?

Here are some of the most main reasons why your emails bounce back.

Your recipient’s inbox is full

When your recipient has a full inbox, your email may be marked as undelivered.

Each ESP (email service provider) has a certain capacity of maximum storage, if someone exceeds that, they won’t be able to receive any new email.

If this is nothing like a soft bounce case, you can’t do much about this temporary issue other than wait until your recipient’s storage has enough space again.

This delivery failure is very common.

If you don’t want to wait, you can contact your recipient through a different medium.

Non-existent email address

It is very common for emails to bounce back when the recipient’s address doesn’t exist.

here are two reasons for this to happen:

  • The email address doesn’t exist at all
  • The email address has been misspelled

When you send an email to an invalid email address, you’ll receive an auto-reply message from your email service provider informing you the email address wasn’t found.

It’s either the mail address has typos, or it isn’t valid anymore.

Out of office/Auto-reply

In some cases, when you send an email to a recipient, you receive an automated email that sounds something like: out of office or “OOO.”

This is very common when your recipient’s email address is a professional one and they’re on vacation, they set up an auto-reply email informing their email sender they’re off duty for the being time.

Auto-reply emails make your emails bounce back after it has been delivered.

This is a chance your recipient might see your message when they are back in the office.

In that case, all there is to do is to wait until your recipient gets back and hopefully read your email.

There is another case that which if you keep receiving the same auto-reply over and over again, for a long period of time, you should remove the recipient from your email list to avoid being a spammer.

Blocked email

Blocked emails are another cause to make emails bounce back.

Blocked emails happen with government institutions or schools with strict email servers and block your emails.

Your recipient’s mail server block emails to prevent spamming attempts.

Here are a few reasons why your email might get blocked or undelivered:

  • If the recipient’s server is skeptical about your emails, you can be flagged as suspicious, which will trigger spam filters and your emails will be blocked and end up in the spam folder.
  • To avoid being categorized as a spammer, you can authenticate your email, making a trustworthy domain name system (DNS) and respecting the sender policy framework (SPF).
  • You can also pay attention to the words in your email’s subject line or body as they might have a spam trigger word.

Bouncebacks and undelivered emails have a great impact on the click-through and open rates of your cold email marketing campaign.

Types of Email Bounce

Email bounces are two categories:

  • Soft bounce
  • Hard bounce

Let’s dive deeper into the meaning of these two terms.

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1-Soft bounce

Soft bounces mean that your email was bounced temporarily.

Soft bounces are not serious as hard bounces.

Here are the common reasons that cause soft bounces:

  • A full inbox
  • An out of office status
  • The email server is down or offline
  • The email message is too large

2-Hard bounce

Hard bounces are when your email has been permanently rejected by your recipient’s server.

Hard bounces are more serious than soft bounces.

Hard bounces can cause a major problem for your email’s deliverability.

Hard bounces happen for a number of reasons, such as:

  • An invalid email address
  • A non-existent email address
  • Blocked email service providers

There are two bounce types that you need to be aware of when you receive a non-delivery report or an error code.

Whether it’s easy or hard to solve a bounced email, bounced emails will badly influence your bounce rate.

What is an Acceptable Email Bounce Rate?

An acceptable email bounce rate is a maximum of 3% for your email marketing campaign.

However, this depends on the industry you’re in as well as the type of email campaign you’re running.

If your bounce rate is higher than 3%, then you need to pay attention and look deeper into it.

Make sure to keep in mind the type of campaign you’re running.

It’s normal for an email marketing campaign to have lower bounce rates than a cold email campaign.


In an email marketing campaign, you have a list of subscribers who willingly signed up their email addresses.

In a cold email campaign, you found the prospect’s email address online, after searching for it.

In this case, you need to use an email verification service to validate email addresses.

An email verification service will help to keep your bounce rates are as low as possible and protect your sender reputation.

How to Reduce Your Email Bounce Rate

If your email marketing campaign is having a higher-than-usual bounce rate, here are the ways to help you undo that.

#1: Use a double opt-in

Using a double opt-in system is a very practical strategy so that only valid and active email addresses sign to your email list.

double opt-in is when a new subscriber signs up for your newsletter, you send them a confirmation email to validate their email address before adding them to your email list.

#2: Authenticate your domains

Authenticating your email domain will mark you as trustworthy to email service providers.

Authenticating your email domain will increase your deliverability rates, therefore decreasing your bounce rates.

Sadly, research shows that less than 40% of emails use SPF, DKIM, and DMARC.

SPF, DKIM, and DMARC are common methods of email authentication.

Authenticating your email domain will improve your email sender reputation, which is something that your recipient’s email server will take into consideration when receiving your email.

Authenticating your email domains helps to keep your bounce rates as low as possible.

#3: Avoid spammy emails

If your emails end up in spam too often, this will harm your sender reputation and will cause many of your emails to be undelivered.

If this keeps on repeating, you might even be blacklisted into a database where ESPs classify potentially spammy and suspicious email senders.

Here are some tips to help your emails avoid the spam folder:

  • Do not use common spam words
  • Do not send bulk emails
  • Do not have misleading sender information

The more email providers that trust you, the lower the chances of your email getting flagged as spam, which will decrease your bounce rate.

#4: Clean your email list ( Email Inspector)

I might be pointing out the obvious, but most emails marketers forget to regularly clean their email lists.

Over time, an email list keeps getting clogged with inactive and invalid email addresses which block your emails from being delivered to your recipients.

It’s important to clean your email lists regularly, remove toxic email addresses and decrease your bounce rate.

You can do this manually by checking your email list for toxic accounts, but this process is very time-consuming.

You can always use the help of an email verification service like Email Inspector.

Email Inspector can help you not only reduce your bounce rate but also increase the engagement rate and deliverability of your email marketing campaign.

Email Inspector has other features to help your email campaign reach its full potential.

Email Inspector also offers a flexible range of prices to adjust your budget and you won’t have to break the bank.

Check for more details.

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