A little more analysis, a little more insight… Exploring email marketing better

What is email bounce and how to reduce email bounce rate

How to reduce email bounce rate is one of the most common challenges digital marketers face today. The ROI of your email marketing campaign can go down seriously if you aren’t within the acceptable email bounce rate range.  

Before discussing the ways to control email bounce rates, let’s quickly understand the meaning and types of email bounces.

What are bounced emails?

Bounced emails are undelivered emails returned to the sender. That’s because your subscriber’s email server rejected the email you sent to them. 

Bounced emails are, therefore, failed emails because your email didn’t reach the person or the organization you wanted to reach. Whether you’re a not-for-profit charity hoping to raise funds or a business enterprise trying to get more clients, you lost a chance to connect with your intended audience.

How email bounce rates affect your marketing campaign?

Paying attention to the rate of bounced emails is important for a variety of reasons. Here’s some of the reasons you need to keep a close watch on bounced emails and ensure they remain absolutely within safe limits:

  1. They can reduce your overall email delivery rate
  2. They lower your sender reputation in the eyes of ISPs
  3. Bounced emails hurt your email marketing ROI
  4. They can cause you to be labelled a Spammer
  5. Your Email Service Provider can penalize you or decline carrying your mail
  6. If left unattended for a long time, email bounce can cause serious problems with the law, like with the US CAN-SPAM Act, among others

What are the types of Email Bounces?

There are two kinds of email bounces: Email Bounce

  1. Hard Bounce
  2. Soft Bounce

What is Hard Bounce?

Emails that bounce because those email addresses either no longer exist or are incorrect are called Hard Bounces. No matter how often your ESP tries, the email will not be delivered since the email address does not exist in the first place.

Think of them as permanently unreachable addresses. If, however, your campaign shows too many hard bounces, probably your emails are hitting the Spam Filter of recipient.

Some of the reasons for Hard Bounce include recipient server has blocked incoming email, the address is incorrect, the domain is incorrect or the email address no longer exists.

What is Soft Bounce?

Emails bounced because the recipient’s server was down or her mailbox is full are called Soft Bounces. Your ESP may try delivering your emails, but will most likely abandon efforts after approximately 5 failed attempts.

Soft Bounces aren’t nearly as bad as hard bounces, but they can certainly reduce your delivery rate, to say the least.

Soft Bounces occur when the recipient’s email server is down or offline, the email size is larger than what the email server permits or the mailbox has exceeded its capacity.

How can you reduce email bounce rates?

Now that you know the basics, let’s focus on the most proven methods to keep your email bounce rate low.

Here are the seven tactics to reduce email bounce rate and improve your email deliverability:

1. Use double opt-ins. Always

Use Double Opt-ins The first step starts even before you send out your email. It focuses on how you append email addresses to your mailing list.

Anyone who keys in her email address to join your mailing list must be first sent an email. The recipient must agree (typically by clicking on a link in the email) to keep receiving your emails.

This action serves two purposes:

  1. Firstly, the email tests whether the address was typed correctly.
  2. Secondly,  it ensures the recipient of the email is the same person who keyed in the address.

2. Start only with a clean email list

Clean your email list to reduce email bounce

One of the key reasons why email verification is so crucial for marketers is that it follows email marekting best practices and helps you continue sending campaigns. If your email list isn’t clean, you’ll soon begin to see unusually high email bounce rate.

Most likely some API or tool already cleaned your database. Besides, you already have a double-opt in so ideally you shouldn’t worry, right?

Well, not exactly. May be someone joined your database before you started double-opt in. May be some email addresses are no longer valid today.

Estimates vary, but in B2B cases, it is estimated around 23% addresses die every year. So it’s always a great idea to kick-start your email marketing campaign with a cleaned list.

To stay safe, experts recommend that you should clean your list at least three times a year. Also, make sure you verify every new email address that’s signing up before you add it to your email list.

3. Prime your IP to success by starting small and accurate

Prime IP to reduce email bounceThis escapes the notice of most marketers.

Your IP must establish a reputation of being ‘good’ and ‘reliable’ so that ISP filters don’t doubt your authenticity. So how do you build that kind of reputation?

It’s a smart idea to start your email campaign by sending out emails in smaller batches to addresses that are absolutely in the loop and fully engaged. Basically, start by sending out emails to a small number of people who you know  will open your emails and not mark them Spam.

The ISP filters notice your emails didn’t bounce, were not marked Spam, and got a high open rate. Now it starts trusting you.

Do this for increasingly bigger sizes and ISP filters will start trusting you fully.

4. Use email authentication

Authenticate to reduce email bounceService providers like Google, Microsoft and AOL, amongst others, use a specific form of authentication when checking incoming email. If the incoming email fails the authentication test, it will most likely land in the Spam Folder.

To avoid this happening to your emails, it’s best to get your emails authenticated.

At least two types of authentication are recommended: SPF and DKIM.

SPF (Sender Policy Framework) is basically a DNS text entry. It shows servers(IPs) that are considered safe to send emails for a specific domain. SPF helps a domain owner insert a file or record. This entry is cross-verified by the recipient’s server. This mechanism allows receiving email servers to verify the incoming mail from a domain comes from a host authorised by the domain’s administrators.

DKIM (DomainKeys Identified Mail), on the other hand, is a mechanism that ensures the message has not been altered from the time it left the sender’s servers. DKIM implants a DNS entry or information inside the email. This embedded or implanted entry inside the email is extremely difficult to counterfeit. This will be used by the recipient’s server to verify that all’s well with the message contents.

Put together, SPF and DKIM not only bring a strong authentication process, they also make your email marketing campaign more professional and authentic.

Finally, there is DMARC (Domain-based Message Authentication, Reporting and Conformance). It fits inside the recipient’s email server authentication process. If the incoming mail fails the SPF and DKIM tests, the DMARC reports to the domain-owner registered with the DMARC records and conveys that the authentication tests have failed.

5. Keep tracking if you have fallen out of favor

This is completely a back-end activity.Don't get blacklisted

From time to time, you will need to keep checking whether you or your email provider have been blacklisted by DNSBL.

There are spam databases and blacklists maintained by various agencies. They diligently track spammers and add servers (IPs) or domains of suspected spammers. 

For instance, Spamhaus maintains a database of IPs that are spammers or otherwise engage in some harmful activity. Such database are called blocklists. A huge number of email inbox providers use these blocklists to filter out unwanted or dangerous emails. We wrote a post on everything you need to know about Spamhaus.

There is one thing you need to understand here: these databases will not get in touch with you in advance when they mark you a spammer. That means it will be your responsibility to keep track of whether you’ve been blacklisted, whatever the reason. If blocked, you’ll begin receiving bounces, provided your recipient server is using that specific DNSBL.

6. Your email shouldn’t look like Spam

Don't look like spamEmail servers are always sniffing around for signs of Spamming. That’s because they want the recipients to have the best of experience and protect them from as many Spammers as possible.

A choice of a single phrase can oftentimes make the recipient’s server classify your email as Spam. For instance, many experts advise marketers to stay clear of trigger words – words that are likely to raise eyebrows and question your email’s authenticity.

In our search on how to write great email subject lines, we often forget that words like, “Online degree” or “No investment” are dangerous when used in Subject Lines. There are many more words you’ll want to stay clear of; perhaps you’d like to read this HubSpot post which has a list of spam-trigger words.

7. Segment your email list


Email segmentation helps fight email bounce more often than you’d imagine. That’s because segmentation means more personalized content. And recipients love personalized content, which is a positive signal for email servers.

Imagine a pizza delivery service. Different patrons prefer different kinds of pizzas. The pizza joint won’t do very well if it were to sell only type, one size of pizza, right?

It can segment its patrons in at least three different ways:

  • Based on sizes served: Barry, a single student orders a smaller size, compared to Michelle who orders for her family of four
  • Based on types of pizza: Bill prefers more veggies while Hillary prefers double-cheese pizzas
  • Based on pricing: Ronald is price-consicous and avoid extra toppings while Nancy loves to try premium toppings

You can add more to this list (e.g. those who order pizzas only on Saturdays). And for every segment you add, your email can become more personalized. personalized-email-message

Which also means you’re protecting yourself from email bounce.

Closing words

The fact is, even the most careful marketers sometimes face email bounce. Of course, their agility and technical understanding define how quickly they get out of it.

While spammers try to circumvent the recipients’ mail servers with shrewd tactics, the servers themselves are constantly learning. That means what was considered safe yesterday may be a no-no today.

To the marketer it means being constantly alert, seeking out what servers consider unhealthy and making sure their own emails are free from any inadvertent slips.  

If you follow best practices of email marketing and the tips mentioned above, ideally you don’t have anything to worry about. However, it’s always better to be alert.

What all things do you do to prevent Email Bounces?


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