Email Bounce Explained: 101 Guide For 2024

What Is an Email Bounce?

An email bounce, also called an ‘email bounce back’, occurs when an electronic message is unable to be delivered to the recipient's mail address and is returned to the sender with an automated message indicating a delivery error. This can happen for a number of reasons, which we discuss in detail in the next section of this article.

What you need to know about email bounces right now is that they have a negative impact on your marketing campaigns, as they can affect a metric called email bounce rate, which is the percentage of messages that are unable to be delivered to the recipient's mail address.

A high mail bounce rate can harm the reputation of your mail domain and the IP address from which your messages originate. Internet Service Providers (ISPs) keep an eye on how reputable your domain and IP address are, and they may send your messages to spam or prevent them from reaching the recipient at all if they fall below a certain threshold.

Why Does an Email Bounce? Types of Email Bounces

Not all bounces are created equal, and you need to understand the differences between them to effectively address and reduce your bounce rate.

Soft Bounces

Soft bounces occur when a message is temporarily unable to be delivered to the recipient's mail address. Common causes of soft bounces include:

• Full mailbox: If the recipient’s inbox is full, your message can’t be delivered until some space is cleared by the user. Perhaps surprisingly, this is still a major cause of soft bounces, despite the large storage capacities offered by most major mail service providers.
• Server issues: The recipient's email server is experiencing issues or is temporarily down, preventing the delivery of the message. Most major mail service providers, including Outlook", Gmail, and iCloud Mail, make the status of their servers publicly available, so you can easily check if this is the cause of a soft bounce.
• Excessive message size: The message is too large and exceeds the recipient's mail server's size limit. For example, Gmail users can receive messages that are up to 25 MB large, but Apple limits the users of its iCloud Mail service to just 20 MB.

The good news is that soft bounces often resolve themselves or can be resolved with relatively minor adjustments to the message and/or its attachments.

Hard Bounces

Unlike soft bounces, hard bounces are permanent, and they indicate a more serious issue why a message can't be delivered, such as:

• Invalid address: If the mail address doesn’t exist or is misspelled, the message will hard bounce. For example, sending an email to "jogn@gmail.com" instead of "john@gmail.com" (notice the typo in the name) is guaranteed to cause a hard bounce unless the misspelled address exists and belongs to someone else (in which case the unintended recipient may report it as spam, which is just as bad).
• Domain doesn't exist: Likewise, if the domain name in the mail address isn't valid or doesn't exist anymore (like many smaller providers have done in the past), the email will be returned to the sender as a hard bounce. For example, sending an email to "john@gnail.com" (notice the typo in the domain name) will result in a hard bounce because the domain "gnail.com" does not exist.
• Blocked email or IP address: Sometimes, a message will hard bounce because the sender's mail address or IP address has been blocked by the recipient's email server. This usually occurs if the server has flagged the sender as a source of spam or malicious content.
• Email authentication issues: If there are problems with the configuration of mail authentication methods like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance), a message can also hard bounce. These technologies are used to verify that the sender of an email is authorized to send messages on behalf of a domain.

Hard bounces are more harmful to your email reputation than soft bounces, and it's important to regularly remove the addresses associated with them from your mailing list to maintain a good email bounce rate.

How to Reduce Email Bounces

Now that you understand why bounced emails are so harmful to anyone who regularly sends messages in bulk, you're understandably eager to learn how to reduce your bounce rate. But first, you need to know the answer to the question: What is a good bounce rate for email?

While opinions among experts vary slightly, we can generally say that anything below 2% is fantastic. This means that for every 100 messages you send, a maximum of 2 should bounce back. On the other hand, anything above 5% is a cause for concern.

With that in mind, here are some practical solutions to reduce your email bounce rate:

Clean Your Email List Regularly

The most effective way to reduce your email bounce rate is to regularly clean your email list. This involves removing any mail addresses that have resulted in hard bounces, as well as any addresses that have not engaged with your messages for a long time.

An email bounce tester can help you check if a message will bounce and remove it from your list if it does. Many such tools are available, but not all are legitimate or equally accurate. Verified.email offers an exceptionally reliable and easy-to-use email bounce test tool to help you proactively maintain a cleaner, more efficient mailing list.

Implement a Double Opt-In Process

Another way to reduce your email bounce rate is to implement a double opt-in process for new subscribers. This involves sending a confirmation email to the subscriber's mail address and requiring them to click a link to confirm their subscription.

The goal here is to check that the address entered by the new subscriber is correct and that they are genuinely interested in receiving your messages. As a result, a double opt-in process not only reduces the number of bounced emails but also the number of spam complaints and unsubscribes.

Use a Reputable Email Service Provider

Selecting a reputable email service provider can greatly enhance your email delivery rates. These providers have sophisticated technologies and established relationships with ISPs to make sure your messages get delivered to your recipients’ inboxes instead of bouncing back or ending up in spam folders.

Examples of reputable mail service providers include Mailchimp, Constant Contact, SendGrid, and AWeber. Choosing the right provider will depend on your specific needs, such as the size of your mailing list, the complexity of your campaigns, and your budget.

Optimize Your Email Content

The content of your emails can also impact your bounce rate. We've already explained that large messages can cause issues, but suspicious attachments (such as .zip files) or spammy-looking subject lines can also contribute to high bounce rates.

To optimize your message content and reduce the risk of bounces, we recommend you keep your emails concise and to the point, avoid using too many images or other multimedia elements in your messages, and personalize your emails by using the recipient's name and other relevant information.

Level Up Your Email Authentication Game

These days, anyone who wants to send emails in bulk needs to play by the rules set by ISPs and mail service providers. One of the most important rules is mail authentication, which is a way to prove that an email really comes from the sender and not from someone who wants to impersonate them.

More specifically, you need to specify which IP addresses are authorized to send email on behalf of your domain (SPF), add a digital signature to your messages (DKIM), and indicate how you want the recipient's mail server to handle emails that fail the authentication check (DMARC).

Never Buy or Rent Mail Lists

No matter how tempting it may be, you should never buy or rent mail lists. Not only is it illegal in many countries, but it's also a surefire way to increase your email bounce rate and damage your sender reputation.

When you buy or rent a mail list, you have no way of knowing whether the mail addresses on the list are valid or whether the people on the list have given their consent to receive emails from you. Instead of buying or renting mailing lists, focus on building your own email list organically.

Conclusion

Effectively managing email bounces is essential for any successful email marketing strategy. By learning how to clean an email list to reduce a bounce rate and how to fix email bounce back issues, you can achieve higher deliverability and engagement. So take the initiative to apply the practices described in this article and watch as your email marketing transforms into a powerful tool for driving conversions and revenue.

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