What is Email Bounce Rate and How to Keep It Low?

Bounced emails are a regular concern for every business interacting with customers via email. The term “bounced email” implies that it didn't reach the intended recipient. Instead, the message was rejected by the receiving server for whatever reason.

It’s essential to keep email bounce rates as low as possible. A high rate leads to lower customer engagement and lower sales for your business. This article will explain why email bounces occur and answer the most frequently asked questions.

What is email bounce rate?

It is the percentage of emails you send out that fail to reach their intended recipients. Instead, they “bounce” back to you, hence the term. Technically, this means that they are rejected by the addressee’s mail server.

Emails can be bounced for many reasons. It could occur due to multiple spam complaints for your domain. The receiving server may be malfunctioning or unable to process messages. The issue could also be associated with the recipient, e.g., their mailbox storage is full, or the address is temporarily unavailable.

How to calculate bounce rate

The formula is simple. You calculate email bounce rate by dividing the number of bounced emails by the total number of emails you send. Multiply the figure by 100 to express it as a percentage.

For example, if you send 1,000 emails, and 50 of them are bounced, your bounce rate is (50/1000) = 0.05, or 5%.

There are two categories of email bounces: hard and soft. Let’s discuss the difference between them.

What is a hard bounce?

You get a hard bounce when an email is returned to your server because of a permanent error. Any further attempts to send this particular message to the same address are very unlikely to succeed.

The most common reasons for hard bounces are:

• Email address does not exist
• The message is considered spam
• Your domain or IP address is blacklisted

Too many hard bounces can lead to blacklisting of your domain. Hence, it’s essential to avoid them as much as possible.

What is a soft bounce?

A soft bounce occurs due to temporary errors. Your SMTP server will usually retry sending a soft bounced message without any action on your part. The most common reasons for soft bounces are:

• The recipient’s mailbox storage is full
• Your server is greylisted
• The recipient’s mail server is under maintenance

Soft bounces aren’t as bad as hard ones because the issue can usually be fixed. Yet, you need to avoid them as well, if possible.

What is a good email bounce rate?

2% and below is considered a good bounce rate. This means that for every 100 emails you send, 98 should get to their intended recipients, and only two can be rejected. Anything above that is alarming, and the issue needs to be fixed before it causes serious problems for your email marketing.

How to check email bounce rate

A good email service provider (ESP) should make it easy to see your bounce rates. UniOne lets you monitor all your metrics from a single dashboard, including bounce rates. We update the dashboard in real time so that you can keep track of your bounce rates on the go.

It’s essential to check your bounce rate on a regular basis. It ensures you don’t spend too much time and effort creating campaigns for people who won’t even see them.

Regular monitoring lets you easily notice if your bounce rate is ticking up and tackle the issue before it gets worse.

How to reduce email bounce rate

If your bounce rate is above 2%, don’t fret. You can take actions to reduce it as much as possible.

These actions also apply if your bounce rate is already below the 2% level but you want to keep it even lower to be on the safe side. Reducing the bounce rate requires diverse measures, some simple and some more complex to master. A simple one is getting explicit permission before sending out marketing messages. You can also check your lists regularly to remove addresses with little or no engagement. A more complex method involves using email authentication techniques to help email clients verify your identity. We’ll dive deeper into these methods below.

Verify your existing email lists

Ensure you verify your mailing list to prune invalid addresses. UniOne lets you validate email addresses on your list and ensure they are authentic. You can even add validation to your site’s subscription form, letting users know if they provided an invalid address.

Our platform can tell if an email address:

• Does not exist
• Is not operational
• Is a disposable address
• Is a spam trap
• Is a source of many spam complaints
• Has a typo

Verification ensures that you send messages to legitimate users who can actually respond to them.

Keep your lists clean

Even if an address is initially ok, it may become inoperational later, which will result in bounces. For example, a person might abandon their mailbox, in which case you’ll repeatedly get a “mailbox full” bounce. If the problem persists, there’s a high chance that this mailbox will never be used again.

Luckily, UniOne keeps track of such cases and blocks the address after a few unsuccessful mailings, thus reducing the number of bounces.

Send your mailings regularly

Over one year, about 10 to 15% of all email addresses become unreachable due to various reasons, as our stats show. If you send your campaigns only once in a few months, say, on major holidays, you are guaranteed to encounter problems with high bounce rate. Be sure to employ a more consistent strategy, sending emails to customers at least monthly.

Use permission-based marketing

Consent is the bedrock of email marketing. You must obtain explicit permission from the owner of an email address before sending them marketing materials. Otherwise, they can report your domain for spam and block it, thus increasing your bounce rate.

The best way to ensure you have permission is by implementing double opt-in. You shouldn’t just message an email address added to your list because it may have been added by someone who is not the owner. Instead, send a confirmation email to each new subscriber. This email includes a unique link that the address owner will click to confirm they are actually subscribing to your mailing list.

The good news is that UniOne lets you automate double opt-in and reduce your bounce rates with little effort.

Set up SPF and DKIM authentication

Sender Policy Framework (SPF) and Domain Key Identified Mail (DKIM) are popular email authentication methods. The latter lets you digitally sign your emails, and the former lets recipients verify that an email comes from an authorized server. Authentication prevents spammers and hackers from impersonating your domain.

Let’s see how these techniques work.

• SPF:You create domain name system (DNS) records listing the IP addresses authorized to send messages on behalf of your domain. Whenever a message purportedly comes from your domain, the receiving server validates that it comes from an authorized IP address before letting it pass. Otherwise, it blocks the message.
• DKIM:You use encryption keys to sign your messages. When a mail server gets your incoming messages, it looks up your public key via the DNS system. The server uses it to decrypt the message’s headers and verify their integrity. If the check fails, the email will not reach the recipient.

SPF and DKIM protect your online identity and prevent spammers from abusing your domain. Mail servers will more likely accept your messages if they can verify your identity, reducing bounce rates.

Try to re-engage inactive subscribers

Monitor your mailing lists for addresses that have stopped engaging with you. You can try to re-engage this cohort by sending them appealing messages. You can offer discounts, coupons, perks, etc., to entice them to react to your emails.

However, if you try your best and still observe no engagement from some addresses, be sure to remove them from your list. Pruning disengaged subscribers improves your open rates and eventually reduces bounce rates.

Monitor every campaign’s bounce rate

You should monitor the bounce rate for every email campaign you send out. If you observe bounce rates going up, it means there’s something that needs to be fixed. Inversely, if bounce rates are trending down with each subsequent campaign, you’re on the right track.

UniOne lets you monitor bounce rates for all email campaigns. Our easy-to-use dashboard makes it seamless to monitor your metrics and identify any areas in need of improvement.

How to further improve email bounce rates

We have explained the actions to take if you have a high bounce rate that needs to be reduced. Now, it’s time to learn about more general ways to improve your bounce rate, even if it’s already within the acceptable limit.

These measures are not so complicated. The most straightforward one is to avoid sending spam or imitating spammer behavior in your messages. Also, send emails consistently, update your lists frequently, and test emails before sending them.

Let’s dive deeper into these steps below.

Update your mailing list frequently

As mentioned above, you should update your mailing lists regularly while ensuring all addresses are valid and up-to-date. People don’t keep emails forever, so a valid email address today can become invalid tomorrow.

You should check your mailing lists regularly for any invalid addresses. Delete the ones you detect to improve bounce rates.

How often you should clean mailing lists varies across industries and businesses. You can do it every three months or even monthly; the more often, the better.

Adding new addresses is equally important. New subscribers show better engagement, which improves your sender reputation.

Avoid spammy behavior

This point seems obvious to every email marketer. Avoid sending any messages that could be mistaken for spam. Email services like Gmail or Yahoo Mail use algorithms to check the incoming email for spam. If the algorithm flags your message for a high likelihood of spam, it will be either placed in a spam folder or bounced.

Algorithms work by detecting common tactics employed by spammers. You should note these tactics and avoid them as much as possible:

• Poor spelling and grammar.Spam emails are usually littered with misspelled words and grammatical errors while trying to impersonate a well-known brand. But any well-known brand would hire professional writers to create cohesive emails. Ensure your emails are well-written and free of spelling errors.
• Asking for sensitive information.Never ask customers for sensitive information via email, e.g., phone numbers and home addresses, because this behavior is typical for spammers.
• Subject lines with all uppercase letters.Spammers use all uppercase letters in subject lines to create a false sense of urgency.
• Messages without unsubscribe links.Always include an unsubscribe link in your email’s footer that recipients can follow to remove their address from your list. Otherwise, recipients might mark your message as spam.

Send emails consistently

You should send emails on a regular schedule to maintain engagement with your customers. People have a short attention span and can easily forget that they have once subscribed to your list. In that case, a recipient can mistake your message for spam and report it to their mail service, causing further messages to bounce.

Send messages frequently enough for subscribers to stay engaged with your brand. Two to three emails weekly is an acceptable rate. Yours could be even higher, as with a daily newsletter. Some industries, like fashion, tend to interact more with customers, so you can also send daily messages to customers.

Yet be careful not to send too many messagesbecause that is spammy behavior. This can cause recipients to report you for spam, tanking your sending reputation and increasing bounce rates.

Whatever your sending frequency, it’s advisable to send out emails at set times. For example, if you run a daily newsletter, you can send emails between 2:00 p.m. and 2:30 p.m. each day. A recurring schedule helps build familiarity and anticipation from recipients, while irregular large mailings are more likely to be blocked as spam.

A/B test your emails

A/B tests are controlled experiments where you test multiple versions of the same email to see which one is more successful.

Imagine you run an online store seeking to promote an upcoming sales day to customers. You can create three variants of a promotional email and send them to similar cohorts of customers. The idea is to see which variant generates the most response and why. With this data in mind, you can use the winning approach to generate the best responses from further email campaigns.

You can differentiate your email variants in several ways. It could be something as small as changing the subject line or using different images. It’s advisable to change just a few elements for each variant: this makes it easier to identify what’s driving better responses from a campaign.

A/B testing helps you generate better open, click-through, and conversion rates for your campaigns, increasing your sending reputation and reducing the possibility of email bounces.