Why Do Emails Bounce And How To Reduce Email Bounce Rates

What is a Bounced Email?

What does it mean when an email bounces? A bounced email occurs when you receive an error message in response to an email you sent to somebody. That non-delivery report from your email service provider (ESP) indicates the reason for the failed delivery, reasons that include issues related to the recipient's address, inbox, server, or others.

📌 Email deliverability scored 8 out of 10 in importance for 78% of respondents surveyed by Mailjet. However, only 27% expressed confidence in their knowledge about this metric.

As marketers and business owners, understanding deliverability and message failures is crucial because you can’t achieve your desired outcomes without reaching your target readers. This makes bounce rates a vital email campaign performance metric.

To prevent wasting time, resources, and effort crafting your marketing messages, let's explore the factors contributing to email bounce and how to improve email deliverability.

Why Do Emails Bounce? Types and Common Causes

Knowing the factors that make emails bounce back to your inbox helps you determine the steps for avoiding future failure deliveries. Undelivered emails fall into two categories: soft bounces, which are due to temporary glitches, and hard bounces, which are permanent delivery failures. Let's look at them in more detail.

1. Soft bounces

Some of the temporary issues leading to soft bounces include the factors below. However, if soft bounces keep recurring, you may need to check your email content or the recipient's email server.

📌 Full inboxes

Inboxes that have reached full capacity won't be able to receive new incoming messages. The clean-up of such inboxes facilitates the delivery of fresh emails.

Sample message: "The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered."

📌 Server issues

Emails don't reach recipients when their ESP server is temporarily down or undergoing problems that prevent them from accepting messages.

Sample message: " Requested action aborted – Local error in processing."

📌 Email file size

If the recipient's server has specific size limits per message, emails with a large file size due to images and attachments won't get through.

Sample message: "This message is larger than the current system limit."

2. Hard bounces

Here are some reasons behind permanent delivery failures leading to hard bounces:

📌 Spam filters or security settings

Your recipient's server may reject your email as a security measure if your domain's authentication protocols aren't set up correctly. Also, some individuals or companies install stringent spam filters that block certain email types from being delivered.

Sample message: "Delivery not authorized, message refused"

📌 Invalid address or non-existent domain

You can get a failure notice if the email address is non-existent because the recipient has abandoned the account or had a suspended account for some reason. Misspelled addresses (melissarobins@gmail.con instead of gmail.com) or missing characters (absent @ symbol) can also prevent successful delivery.

Sample message: "User unknown" or "Sender domain not found"

📌 Fake email addresses

Recipients may deliberately provide fake or disposable email addresses to obtain free resources online.

Sample message: "Unknown or illegal alias"

The next step is to take appropriate corrective measures, including knowing how to fix email bounce back issues. Why is this important? Receiving too many email bounces can cause your recipient's ESPs to classify you as a spammer, which can block you completely the next time you send a message.

How to Check if an Email Will Bounce

One of the ways to prevent emails from bouncing back to your inbox is to conduct manual checks and use verification tools. The steps below are worth trying out before we uncover how to reduce email bounce rate.

1. Examine syntax and format

Valid emails follow the basic structure (username@domain.com). Inspect for common mistakes, such as repeated characters or misspelled domains (such as outloook.com instead of outlook.com) or omitted/misplaced dots (gabrie.llandy instead of gabriel.landy)

Verify whether the domain part of the address (after the “@”) is valid by copy-pasting it into your browser. If it opens into an operational website, then the domain is active. You can also conduct a DNS lookup, which confirms whether the domain has mail servers configured to receive emails.

2. Conduct a Google search

An address is most likely active if associated with an account, listing, or social media platform(s) after typing the full email address into the Google search bar.

3. Use an email bounce checker

Choose email bounce checkers, such as VerifiedEmail, to scan your contact list and verify the status of email servers. It automates the manual checks (syntax, format, and domain).

These tools verify Mail Exchange (MX) records and Simple Mail Transfer Protocol (SMTP). MX records indicate which email server will receive the message you sent. Meanwhile, SMTP determines a server's ability to receive incoming messages by sending a “ping” or test email to that email address.

How to Fix Email Bounce Back Issues

Some messages may still bounce back after applying the suggested email verification steps. First, you must read the bounce message, and then determine whether it's a hard or soft bounce.

Afterward, try these troubleshooting tactics to resolve delivery issues right away, especially after identifying troublesome addresses:

1. Remove invalid addresses

Delete contacts associated with hard bounces (undeliverable, suspended, and non-existent addresses).

Check if your email is valid with VerifiedEmail.

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2. Retry sending

Resend messages at a later time for soft bounces. Wait 24 to 48 hours for the first retry and three to five days if you get another soft bounce notice. Some ESPs automatically retry sending after a specific timeframe before marking an email address as bounced.

3. Authenticate your emails

Enable authentication protocols so email providers will recognize messages sent from your domain as legitimate.

One of these protocols is the Sender Policy Framework (SPF). SPF checks whether an incoming message comes from a domain authorized by the receiving mail server's administrators. Meanwhile, DKIM (DomainKeys Identified Mail) is a digital signature that allows the receiving server to verify that the message was sent and authorized by its domain source.

4. Contact your email provider if you appear as blacklisted

Your recipient's email server can blacklist your messages if you have a high bounce rate. Continuously sending messages without dealing with issues, such as authentication, can result in this problem. Or your IP address may have been flagged for spam due to your recipient's strict filter settings.

Check your bounce message for mentions of Spamhaus—an anti-spam blacklist service—and "RBL" or Real-time Blackhole List. Then, report this incident to your provider and request delisting. Using platforms such as MxToolbox and Talos for blacklist detection also helps.

How to Reduce Email Bounce Rate

These strategies can prevent your messages from bouncing in future campaigns and keep your bounce rate as low as possible for the long term:

1. Use double opt-in

Double opt-in requires subscribers to confirm their email address after signing up for your email list. They must type their address, which reduces the chance of having inaccurate or invalid addresses added to your contacts list.

This practice isn't a universal requirement but is recommended in areas covered by the GDPR. Additionally, it has become a widely adopted engagement method because you get subscribers' explicit consent. Thus, recipients are less likely to flag your messages as spam.

2. Clean your contact list regularly

Remove unengaged contacts from your contacts list regularly besides deleting fake and misspelled addresses. Automate this process by using email list cleaning tools like VerifiedEmail.

3. Segment and re-engage inactive users

Segmenting your list can help you customize content based on certain preferences or subscriber profiles, increasing the chances of opened emails. You can group subscribers into segments based on their engagement (click-through and open rates), demographics, and interests.

Moreover, take steps to re-engage subscribers who don't actively read or interact with your messages. You can ask what their preferred topics are or how frequently they prefer to receive messages from you.

4. Avoid using words associated with spam

Proofread your email's subject line and body to replace or delete terms that overpromise ("Double your income," "best price," or "guaranteed") or create false urgency ("Limited time offer," "urgent action needed," or "last chance"). Your message might also be considered spammy if it contains too many boldfaced or capitalized characters.

5. Know the acceptable bounce rate

What’s a good bounce rate for email? The general benchmark is 2% and below. Here's how to calculate the bounce rate email manually:

6. Monitor and improve your sender reputation score

Tools are available to help you track your email-sending metrics, such as delivery rates, open rates, and bounce rates. A healthy score will keep you in good standing with Internet and mailbox providers. In contrast, frequent bounces and spam complaints can make your email sender reputation decline.

7. Regularly test your email deliverability

Email deliverability testing software can check various aspects of your email simultaneously, from authentication (to ensure it won't be identified as spam) to content (for spammy words or images with very large file sizes) and a sample of your contacts list.

Conclusion

You can't leave email deliverability issues unchecked because they can chip away at your performance and finances. According to a recent WebFX poll, 60% of US-based marketers earmark $51 to $1,000 monthly on email campaigns.

Learning about soft and hard bounces is the first step to taking a proactive stance against email delivery failures. Follow this up with email verification and regular list cleaning, which you can achieve together through automated tools such as email bounce checkers and verifiers like VerifiedEmail. Apply our tips for message deliverability to see a boost in sender score and campaign ROI.