Why Are Your Emails Bouncing? Understanding the Reasons and How to Prevent It

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Written By Stephen


Welcome to our latest blog post! Today we’ll be talking about email bounce and why it’s a significant issue for businesses that rely on email to connect with customers, share important information, and promote their products or services. If you’re running an email campaign or communicating with customers via email, you want to ensure that your emails are being delivered successfully to the intended recipient. However, sometimes emails bounce back, which can be frustrating and confusing. In this article, we’ll discuss the common reasons for email bounce and provide actionable tips to prevent it from happening, so that you can improve your email deliverability and engage more effectively with your audience. So, let’s dive in!

Reasons for Email Bounce

When an email fails to reach its intended recipient and is returned to the sender, it’s called an email bounce. There are several reasons why emails bounce back. Some of the most common reasons include:

1. Recipient does not exist
One of the most common reasons for email bounce is when the recipient’s email address is incorrect or does not exist. This can happen if you mistype the email address or if the recipient has changed their email address without informing you. In such cases, the email server will return the message with an error indicating that the recipient’s email address is invalid.

2. Mailbox is full
If the recipient’s mailbox is full and has exceeded its storage capacity, any new emails that are sent to that mailbox will bounce back. This can happen if the recipient hasn’t checked their email for a while or if they receive a lot of emails regularly.

3. Spam and virus filters
These filters are designed to block emails that are considered spammy or contain viruses or malware. If your email triggers one of these filters, it will bounce back. This can happen if you use certain spam trigger words or phrases in your email, or if your email contains suspicious attachments.

4. Content blockers
Content blockers are similar to spam and virus filters, but they block emails that contain specific types of content that the recipient has chosen to block. For example, the recipient may have chosen to block emails that contain explicit language or inappropriate images.

5. Oversized attachments
If you attach a file that is too large to the email, it will bounce back. Most email services have a limit on the size of attachments that can be sent.

6. Blacklists and reputation management
Email servers use blacklists to identify and block emails from senders who have a poor reputation for sending spam or malicious emails. If your IP address or domain name is on a blacklist, your emails may bounce back.

7. DNS Failure or other server errors
If there is a problem with the DNS (Domain Name System) or if there is an error on the email server, your email may bounce back. This can happen due to various reasons, such as misconfigured DNS records, expired SSL certificates, or server maintenance.

Understanding the reasons for email bounce is the first step in preventing it from happening. In the next section, we’ll discuss the consequences of email bounce for businesses.

Consequences of Email Bounce

Email bounce can have several negative consequences for businesses that rely on email communication, especially if it happens frequently. Here are some of the consequences of email bounce:

1. Lost sales
If your emails are not reaching their intended recipients, you may be missing out on potential sales opportunities. This can lead to decreased revenue and lower business growth.

2. Decreased customer engagement
Email is a critical tool for engaging with customers and building relationships. If your emails are bouncing back, you’re missing out on opportunities to connect with your customers and to further build those relationships.

3. Damage to reputation
When emails bounce back, it can indicate to email servers that you’re not a reputable sender. This can damage your reputation as an email sender and can lead to more emails being blocked or marked as spam. Over time, this can severely harm your ability to communicate with your customers and prospects via email.

4. Wasted time and resources
When your emails bounce back, it can be frustrating and time-consuming to identify the problem and resend the email. This wastes valuable time and resources that could be better spent on other business activities.

Overall, email bounce can have a significant impact on your business’s bottom line, customer engagement, and reputation. In the next section, we’ll discuss some tips to prevent email bounce and ensure that your emails are delivered successfully to your customers.

Tips to Prevent Email Bounce

Preventing email bounce requires a proactive approach and consistent effort to maintain a good sender reputation. Here are some actionable tips to help you prevent email bounce and ensure that your emails are being delivered successfully:

1. Verify email addresses
Before sending an email, double-check the recipient’s email address to ensure it’s accurate and up-to-date. You can use email verification tools to first validate email addresses and ensure they exist and are active.

2. Monitor your email list
Regularly monitor your email list and remove any email addresses that have bounced back in the past. This will help keep your email list clean and reduce the likelihood of future bounces.

3. Keep email sizes manageable
Avoid sending oversized attachments that can cause emails to bounce back. Check the email service provider’s attachment size limit and compress large files before attaching them or try uploading the attachments to an online file storage service like Google Drive instead.

4. Avoid spam trigger words and phrases
Avoid using spam trigger words and phrases in your email, such as “earn money fast” or “get rich quick.” These words and phrases can trigger anti-spam filters and cause your email to bounce back.

5. Authenticate your email
Authenticate your email domain by setting up DKIM, SPF, and DMARC records. This will help to prevent your emails from being marked as spam or rejected by email servers.

6. Monitor your sender reputation
Monitor your sender reputation by regularly checking blacklists on websites like MXToolBox and ensuring that your email campaigns adhere to best practices. Avoid sending too many emails too quickly, and only send emails to recipients who have opted in to receive them.

7. Use a reputable email service provider
Use a reputable email service provider such as Cloudbase that scans and filters all inbound and outbound emails via external providers, MailChannels and SpamExperts before it arrives or is sent to the intended recipient. We ensure that all emails are delivered without any blacklisting issues.

By following these tips, you can prevent email bounce and ensure that your emails are being delivered successfully to your customers. This can help you maintain a good sender reputation, increase customer engagement, and grow your business.


Email bounce can be a frustrating issue that businesses face when trying to communicate with their customers and prospects. However, understanding the reasons for email bounce and implementing the tips we’ve discussed can help prevent it from happening and ensure your emails are delivered successfully.

Remember to verify email addresses, keep your email list clean, avoid oversized attachments, avoid spam trigger words and phrases, authenticate your email domain with DMARC, DKIM, and SPF, monitor your sender reputation regularly, and use a reputable email service provider. By following these actionable tips, you can reduce the likelihood of email bounce and ensure your emails are being delivered successfully to the intended recipient.

At Cloudbase, we understand the importance of email communication for businesses. That’s why we offer reliable and secure email hosting plans to ensure high deliverability rates and help our clients avoid email bounce. Contact us today to learn more about our email hosting solutions and how we can help your business succeed.

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