Bounced Back Emails: What Are They And How To Fix Them?

You send a well crafted email to a bulk list of subscribers to market your product and within minutes an annoying message springs up in your inbox stating the email has not been delivered.

This message is called Bounced back emails or Bounce Notification.

In today’s digital era, email marketing campaigns are one of the most crucial parts of promoting your business. When you’re looking at improving your outreach with your customer base, it is extremely frustrating for a marketer to face something called bounced back emails.

What is an email bounceback?

Bounced Back Emails

An email bounceback is an automated communication sent from a service provider to inform the sender that his message cannot be successfully delivered to the intended recipient.

Every day several billion email bounces happen. This means almost billions of emails never reach their destination, literally pouring away the hard work in crafting these emails.

It is acceptable to a certain level for bounces to be a part of email marketing, but it doesn’t mean that you have to always deal with it.

How to identify an email bounceback message?

A bounce-back message typically looks like this.

Bounced Back Emails

As you can see from the image above, the mail service provided has mentioned the exact cause of the bounce back.

Major service providers such as Gmail, AOL mail and so on give the user recommendations to fix the issue.

These are several reasons that determine an email bounce back. Some of the reasons include:

  • The non-existence of the email id
  • Misspelt email id
  • Irregular characters in the email id
  • Unnecessary spaces in the mail id
  • Server issues etc.

What is an email bounce rate?

Bounced Back Emails

Source:crazy domains

Email bounce rate is the total number of emails that have bounced back divided by the total number of emails you have sent, expressed in percentage.

How to calculate it?

It can be calculated in the following steps:

  1. Calculate the total number of emails you have sent.
  2. Calculate the total number of emails that have bounced back.
  3. Divide the total number of emails sent by the total number of bounced emails.
  4. Multiply the result by 100 to obtain the result as a percentage.

Say, for example, if you have sent 3000 emails, and 300 of them have bounced back.


So you can say that your bounce rate is 10%.

The graph below shows the average marketing email bounce rates in the United States.

Bounced Back Emails

Source: Statista

The average email bounce rate is highly dependent on the industry, and on an average, it is somewhere between 2% and 15%. Ideally, it should be kept below 10%.

Types of bouncebacks

Generally speaking, bounced back messages can be broadly classified into two:

1. Hard Bounces

Within this category, the email is rejected on the spot. This is usually caused due to the permanent non-delivery condition of the email.

This is due to a few reasons such as:

  • Missing or invalid email id.
  • Non-existence of the recipient’s domain.
  • Unknown recipient.
  • Error in typing the recipient’s email address.
  • Network malfunction at the recipient’s end.
  • Blocking by the recipient’s mail server.

2. Soft bounces

Soft bounces are a temporary issue, and the chances are high that it will be automatically fixed in time without much intervention from the part of the sender.

You might be able to send the message and get it successfully delivered without much hassle if you try after some time.

Some of the reasons include:

  • Mailbox is full.
  • Change in email id.
  • Mailbox is abandoned by the user.
  • Mail server of the receiver is down.

A soft bounce will be turned into a hard bounce if the email is not delivered successfully after repeated attempts.

What are the top reasons behind an email bounceback?

Contrary to popular belief, most of the time email bounceback occurs due to some issues which can be fixed easily.

Let us sift through some of the issues:

1. Error in the Email address

This is one of the most common errors in a bounceback email.

If the bounce back is marked as “non-existent email address,” the chances are high that the email address could have a typo or the recipient is no longer using the mail id.

Make sure to proofread the mail ids, as even a change in a single character, could cause an address error.

There is also a chance that the user deliberately gave a false email id, which is most likely to happen if you are offering something online in exchange for the user’s email id.

If the bounceback is from official corporate ids, it simply means that the user has left the organisation and the IT team has blocked their mail id.

Sometimes, this issue could also happen from an outdated email id, and the user would have transitioned to the new one.

2. Mailbox is Full

Bounced Back Emails


Mailboxes have limited storage capacity, and if the number of mails exceed beyond the standard capacity, the mail service provider will bounce all the incoming mails to the delivery server.

Another reason is that your email could be taking too much space in the recipient’s mailbox.

For example, if you are trying to send an attachment along with the mail, the recipient’s mail server is most likely to bounce back your email if the attachment size is beyond the prescribed limit of the mail server at the recipient’s side.

In such a scenario, you could compress your file size using a a compressing software, split it into several emails or use any other online file sharing solutions like dropbox.

3. Blocked emails

Bounce back is a common occurrence in servers where there are IP restrictions.

This is a common occurrence in government organisations, schools, or industries.

Bounced Back Emails

Source: TED ideas

Some recipient servers like organisational or corporate servers allow only specific IP addresses to deliver the emails due to several reasons including internal security issues.

If you are getting bounce backs while sending emails to corporate email ids, the simple reason is that their mail servers are blocking your email.

If this is the case, you will have to make sure that your IP address is whitelisted in the recipient mail servers.

4. Auto-response is on

This is a unique case which does not necessarily classify into soft or hard bounce categories.

Auto-response usually occurs when the recipient is out on vacation.

The moment your email hits his inbox, the email service provider will instantaneously send you back an auto-response. However, one good thing about this is that you can ensure that your email hits the recipient’s inbox.

You might be wondering about the actual reasons behind this issue.

Sometimes it is likely the email addresses that keep on auto-replying could be abandoned by the user. If the bounce back continues for a few months, it is advisable to consider removing it from the bulk mailing list.

5. The recipient has blocked the email address

If the recipient is no longer interested in receiving your email, he could block or spam your email. If he has blocked your email upon reception, an automatic bounce will be generated.

6. Recipient server issues

Issues at the receiving mail server could be the prime reason for undeliverable emails. This belongs to the soft bounce category.

Undelivered emails mean that an issue is faced by the recipient side email server.

These could include:

  • Server crash
  • Periodical server maintenance
  • Overloaded servers or
  • Temporarily offline

This type of issue could belong to either hard or soft bounce category depending on whether the mail deliverability later.

Try resending the mail a few more times. If you are sure that it did not hit the recipient's inbox after repeated attempts, it’s better to pull it out of your bulk email list.

7. Other factors

In the above six steps, almost all reasons for bounceback are covered. However, it has been noted that bounce backs can even occur due to some unknown reasons.

If such is the case, it is better to monitor the IP address and make sure that the bounce backs are not recurring.

It would also be wise to remove the mail id from your bulk mailing list.

Steps to reduce email bounce backs

Bounced Back Emails


At a global level, more than half of the world's population is using emails.

Studies have shown that the total number of emails sent and received per day is expected to hit a peak of nearly 347 billion by 2020. This makes email marketing an excellent strategy to increase brand awareness.

Bounced Back Emails

Source: Statista

Research on spam indicated that more than half (55%) of the global email traffic are spam messages. Tackling the complex problem of dealing with hard and soft bounces should be a crucial part of your email marketing strategy.

A rise in the number of bounces could impact your deliverability and affect your future prospects as well.

The following are some of the tips to ensure that your email hits the intended recipients and to minimise your bounceback rate.

  • Regularly keep a check on spam databases to ensure that your email account has not been flagged.
  • To reconnect with bounced subscribers, use some of the alternate sources such as dropping a postcard via snail mail and asking to update their mail id, or through a simple phone call.
  • Tracking the engagement pattern of your subscribers and schedule your emails precisely according to that.
  • Keep your emails in an excellent format and use testing tools such as,, etc. to make sure that the spam filters won’t swallow your target emails.
  • Clean up your list regularly. Your email marketing list is continually evolving, and a rigorous monthly check-up is needed to ensure that you have all the working email ids for your campaign.
  • Regularly test your email address to ensure that they are working correctly.
  • Monitor the bounceback rate based on domains and make sure to look for patterns that could indicate a problem with a particular set of domains.

Bottom line

If you are new to email marketing, you need to accept the hard truth that it is almost impossible to reduce the bounce rate to zero.

Bounces are meant to happen, but the silver lining in the story is that you can be prepared to reduce the number of bounces happening over every email you have sent.

By carefully reviewing the bounce reports and periodically dumping non-responsive email addresses, you can ensure that your hard work of carefully crafting the emails won’t go waste.