
When exploring email marketing for your business, you’ll encounter many new concepts, including bounced emails. You might ask, “What is a bounced email?” and “Why does it occur?” It is an unwelcome issue for new email marketers, but one you can avoid.
You’ll learn what bounced emails are and why they occur. Additionally, you’ll discover how to avoid them and improve your email deliverability, so you can maximize your ROI (return on investment) from your digital marketing efforts.
Understanding Email Bounces

Email bounces can cause your email marketing campaign to fail. To prevent this, let’s learn more about this concept and how it impacts your campaign.
What Is an Email Bounce?
An email bounce occurs when an email fails to deliver to the recipient’s inbox. This failure is often due to fake addresses, temporary server glitches, full inboxes, etc.
Also, the email server sends a Non-Delivery Report (NDR) or bounced-back mail to notify the sender of the failure. This error message informs the sender of the reason for the bounce.
Additionally, NDR comes with bounce codes. Hard bounce codes begin with a 5 (e.g., 542), while soft bounce codes start with a 4.
Email bounces are more than minor setbacks. They’re warning signs, notifying you of potential issues with your email strategy.
Understanding these digital barriers is crucial to maintaining a good customer relationship.
Types of Email Bounces
Hard bounces and soft bounces are the two types of email bounce categories. Here are more details about each.
What Is a Hard Bounce in Email?
Hard bounces occur when there’s a permanent reason for email delivery failure. This failure is due to non-existent email addresses.
Also, if a recipient blocks you, it results in a permanent failure. This permanent issue requires immediate attention to preserve your sender’s reputation.
What Is a Soft Bounce Email?
Soft bounces are temporary failures in email delivery. A server glitch, large messages, or a full recipient inbox often causes them.
Also, spam filters can block your emails, causing a soft bounce. Unlike hard bounces, soft bounced messages might get through on a second trial.
Impact of Bounced Emails

Bounced emails affect your email performance and your sender’s reputation. High bounce rates alert email clients that you’re an irresponsible sender.
This situation causes email service providers (ESPs) to block your emails. Still, they can send them to spam folders.
It also leads to poor sender reputation and decreases email deliverability. Moreover, it distorts your email marketing metrics and wastes your resources.
5 Common Reasons for Bounced Emails
Emails don’t just bounce. Below are the top five reasons for email bounces:
1. Invalid or Nonexistent Email Address
The most common reason for a bounced email is a nonexistent email address. This can be due to a typo error, a deactivated email account, or fake email addresses. Invalid addresses cause hard bounces because messages can’t reach an inbox that doesn’t exist anymore.
To manage this issue, effect real-time email validation on your sign-up forms to detect typos in addresses. Also, use a double opt-in process to verify the authenticity of an address.
Additionally, use email cleaners to detect and remove invalid addresses from your subscriber list. A few examples of email cleaners include Kickbox, EmailListVerify, Mailercheck, etc.
2. Full Mailbox
Another reason for email bounces is a full mailbox. A full inbox is a temporary issue that leads to soft bounces.
Most email providers have limited inbox space. So, when a recipient’s storage is full, it no longer accepts new messages. But once the user clears some space, your messages reach them.
You can resolve this issue with a system built to re-attempt delivery of soft bounces. Many email service providers attempt to send these emails after a while. You can also segment subscribers whose mailboxes are always full. Then, send them separate campaigns to address the issue.
However, consider removing the address if a subscriber’s inbox remains full.
3. Email Server Issues
Sometimes, the problem is with the email server, not you or your audience. Server issues lead to temporary delivery failures, resulting in soft bounce. From routine maintenance to overloaded servers, these technical challenges prevent email delivery.
If you encounter a server problem, you’ll get an error message informing you that the server is busy or unavailable. Fortunately, these issues don’t last for long. Moreover, email systems design tries to resend the emails that encounter such issues.
If the recipient’s server issues persist, contact your mail server or mailbox providers for help.
4. Email Blocked by the Recipient’s Email Server
Your email messages won’t reach your audience if they block you. Subscribers might block you if your content is irrelevant to them. They’re also likely to block you if they don’t trust your brand or find unsubscribing difficult.
Additionally, a blocked email could be due to overzealous spam filters. These filters might block your email even if it’s valid, especially when it contains certain triggers or lacks proper authentication.
Also, spam filters may catch your emails if they have a poor text-to-image ratio. You can use SMTP servers to avoid technical spam filters. Furthermore, institutions with strict rules about what type of emails they receive can block your emails.
To prevent blocking, create high-quality personalized content for your audience. Label your emails as legitimate using appropriate email authentication protocols like SPF, DKIM, and DMARC. Also, make it easy for subscribers to unsubscribe when they lose interest.
5. Email Size Too Large
Many email providers specify the maximum size of emails they’ll accept. If your email exceeds this size, it will not reach your recipient’s mailbox. This limit varies across different email providers. But, a good benchmark is less than 20 MB, including texts, images, and attachments.
Always compress large images without sacrificing quality. If files are too large, use cloud storage services and include a download link instead of the direct file. This process reduces your email size and provides a better user experience.
How to Avoid Bounced Emails
Now that you’ve understood what soft and hard bounces are in email, how do you avoid them in future emails?
It helps to maintain a hygienic email list and optimize your content. Monitoring your email bounce rate and using double opt-in is also a good strategy.
Below are ways to avoid email bounces:
Maintain a Clean Email List
A clean email list is key to optimizing your email marketing efforts. Start by creating a system for regular list cleaning. This step detects and removes invalid email addresses and persistent unengaged subscribers.
Use email validation tools to authenticate email addresses. These tools will catch typos and fake addresses before they litter your list. Also, send re-engagement campaigns to inactive subscribers, giving them a chance to become active or risk removal.
Remember, a small list of engaged subscribers in email marketing is more valuable than a large list of inactive audiences.
Implement Email Authentication
Email authentication is like a digital Identification card for your emails. It alerts email servers that your emails are authentic.
Here are three major authentications you should put in place:
- SPF (Sender Policy Framework): SPF defines which servers are authorized to send email for your sending domain.
- DKIM (DomainKeys Identified Mail): This adds a digital signature to your emails, verifying that they remain intact after transmission.
- DMARC (Domain-based Message Authentication, Reporting & Conformance): This system tells a receiving server what to do with emails that fail SPF or DKIM checks.
Applying these protocols can boost your deliverability rates and reduce the chances of blocked or spammed emails.

Also, it prevents spoofers, spammers, and hackers from getting access to you. Setting these systems up seems difficult, but several credible ESPs offer guidance. They have automated tools to help you implement these authentication measures.
Monitor Your Bounce Rate
Keeping a watchful eye on your email bounce rate is necessary to maintain email health. A healthy bounce rate is under 2%. If your rate goes higher than this, take action immediately!
Many email service providers provide comprehensive analytics that track your bounce rate. They break down the analytics by bounce type and recipient’s domain. You can also calculate your bounce rate by dividing the number of email bounces by the number of emails sent. Then multiply the result by 100.
Furthermore, pay attention to trends in your email metrics. Are you receiving more bounces from the same email provider? Did your email bounce rate experience a sudden increase after a particular campaign? This awareness helps you identify and rectify issues before they magnify.
Optimize Email Content
Your email content also affects your bounce rate and deliverability. Maintain a healthy balance between text and images. Using too many images can flag spam filters. Similarly, bulky text can make readers lose interest.
Also, use ‘alt text‘ to boost accessibility and provide context for images if they don’t load. Personalizing your content for readers can enhance deliverability. When subscribers enjoy your content, they’re more likely to open and engage.

This engagement signals email providers that people want your content. So, don’t just focus on avoiding spam-trigger words but also on creating relevant content.
Use Double Opt-In
Double opt-in is another great process for maintaining a healthy email list. It entails sending new subscribers a confirmation email with a link to verify their subscription.
This step ensures only valid addresses make it to your list. Although this step initially produces a smaller list, the quality of your list will improve. Remember, in email marketing, quality beats quantity.
The Role of Email Service Providers in Managing Bounces
Your email service provider (ESP) plays a major role in managing bounces. Most ESPs have systems that handle hard bounces by deleting the addresses after a failed attempt.
This automatic system saves you the hassle of dealing with these permanent bounces. For soft bounces, ESPs have a retry mechanism that resends emails several times after some time.
This technique increases the chances of your email getting through if you’re dealing with a temporary issue. Also, ESPs provide comprehensive bounce analytics, giving you a clear picture of why your emails are bouncing and the source.
Conclusion
Bounced emails are not the end of your email communication. They’re just a part of the process that you can learn to manage. You can maintain a healthy email bounce rate by keeping a clean email list. Also, optimizing emails, using double opt-in, and tracking bounce rates will help. Avoiding bounces is the right step in establishing meaningful communication with your audience.
Next Steps: What Now?
Now that you’ve understood what a bounced email is, here are immediate actions to take:
- Use email cleaners to maintain a healthy email list.
- Use ESPs to check and maintain your bounce rate below 2%.
- Put in place email authentication settings to confirm your emails.
- Personalize your content to keep readers’ interest.
- Use double opt-in to preserve the quality of your email list.
Further Reading & Useful Resources
Below are useful resources to guide your email marketing efforts:
- DNS records for subdomains are required for proper addressing of websites on the internet.
- Learn how to get free email domains for your business.
- Learn about email subdomains and how to use them for your business.
- Find out how to create a website and empower your digital presence.
- Explore proven email marketing strategies to boost engagement and conversions.
- Understand the average email open rate and how yours compares to industry benchmarks.
- Discover the best time to send marketing emails for maximum impact.
- Learn how to personalize your email campaigns to make every message feel tailored.
- See how AI in email marketing is transforming how businesses communicate with customers.





