Causes Of Email Bounces & How To Solve Them
An email bounce

Causes Of Email Bounces & How To Solve Them

You have probably experienced email bounces before. You put effort into crafting out the perfect email campaign only to receive that dreaded notification. Email ‘failed, bounced or rejected’. Receiving an email with these negative subject lines can be discouraging especially when you have no idea what happened. The confusion only furthers when you cannot understand the techy bounce-back error message. Luckily, most of the issues that cause bounce backs are easy to fix. Before we continue, let’s define email bouncing.

How does email bouncing occur?

An email bounce back occurs when an email does not reach a recipient email server for various reasons. When this happens, you receive a bounce message or a non-delivery report or non-delivery receipt from the recipient email server. This is an automated message with details of reasons why the bounce occurred.

In other words, when you send an email, your mail server attempts to locate the intended recipient’s mailbox on their mail server, in order to transfer the message. If for some reason that connection or transfer fails, your mail server should notify you. This is the bounce back email. It contains;

  • The time and date the message bounced
  • The mail server that bounced it
  • The RFC code and reason for the bounce. According to the RFC, a 5XX code depicts a hard bounce and soft bounces by a 4XX code

Reasons why your emails bounce

Before we get into reasons why your emails fail to reach their intended recipient, there are two types of email bounces.

Email bounce

Soft bounce

A soft bounce indicates a temporary technical problem with the recipient’s mail server or other technical issues. In this case, the email address is correct and the connection to the recipient mail server was successful. However, the recipient mail server could still bounce the email because;

Reasons for soft bounces

  • Your intended recipient’s mailbox is full, inactive, or not configured properly
  • The recipient email server is down or offline.
  • Your recipient’s email server has received too many emails during a period of time.
  • The email message is too large.
  • The domain name does not exist.
  • Email messages blocked due to content.
  • Email message does not meet the recipient server’s policies.
  • Your email messages do not meet the recipient server’s DMARC requirements for authentication.
  • An email message does not meet the recipient server’s anti-spam requirements.
  • Email message does not meet the recipient server’s anti-virus requirements.
  • Email message does not meet the recipient server’s sender requirements.
  • Relaying email between email servers fails
  • An email is not relayed for unknown reasons

Notably, a soft bounce can become a hard bounce when soft bounces occur several times. This is why it is important to address the causes of soft bounces when they occur.

Hard bounce

A hard bounce usually implies a permanent problem with delivering an email. Most commonly, this happens because;

  • The recipient email address doesn’t exist.
  • Recipient email server has completely blocked delivery.

With hard bounces, it is important to remove such email addresses from your list immediately. Mailbox providers can remove emails that suffer hard bounces immediately and automatically. Some add these email addresses to a suppression list. This is a list of email addresses that you don’t want to send emails to in order to protect your sender reputation.

How to reduce your email bounce rate

It’s simple. Use email deliverability best practices.

Keep proper email list hygiene by cleaning out invalid email addresses. Additionally, you should also remove addresses that garner no responses. Do not buy or harvest email lists as these could contain invalid, fake, or inactive email addresses that will get you hard bounces.

Use double opt-in for your email marketing campaigns. Double opt-ins help you confirm that the recipient wants to receive messages from you. It also verifies that the email address is active and valid.

Read more on 10 ways to improve email deliverability

Closely monitor your bounce rates. Analyze your bounce-back messages to find the causes of both soft and hard bounces. With this information, you can anticipate these bounces or fix them before they cause too much damage.

Ensure you have authorized your email client or mailbox provider to send emails on your behalf.

To bypass bounce backs that occur due to the recipient’s email security filters, you can contact them and ask them to add your IP address to their allow list.


Businesses that depend on bulk emails or email marketing can easily reduce bounce rates. This is by practicing proper list hygiene, using opt-in lists, and using proper methods to build email lists. Most importantly, the best solution is using a third-party email hosting provider.

Email hosting service providers specialize in hosting business emails. They can help you effectively purge your lists and immediately drop email addresses that cause hard bounces. They can help you understand bounce-back error messages.

Pepea Email is built for business email communication. Whether one on one or marketing emails, we ensure your messages reach the right mailbox. With Pepea Email Marketing, you can improve your email deliverability, response rates and significantly reduce your bounce rates. You can enjoy a free trial of our email marketing platform by simply visiting our website. Contact us today for the best business email management solutions.

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