Updated on January 26, 2022
You wrote an attractive subject line and created great content and as you start sending your emails, you see a bounce message in your inbox. That is why you should pay attention not just to the open and click-through rates of your email campaigns, but the email bounce rate as well.
Making sure your carefully crafted emails and tailored content, made for your recipients to reach their intended inbox is key.
What is an email bounce rate
Email bounce refers to the percentage of emails that were not delivered to the emails in your subscriber list because the email was returned by the recipient email server.
The error code bounce message attached to the email, states if it was a soft or a hard email bounce.
Soft email bounce
A soft email bounce means that the email was not delivered due to a temporary issue, for example, if the recipient’s inbox is full.
Your email service provider may try to deliver the email, however, be aware that five consecutive failed attempts will result in a hard bounce.
The most common reasons for a soft bounce are:
-
- The recipient has a full inbox
- The email address is currently unreachable
- The recipient server is down/offline
- The email message is too large
- Graylist enabled email server
In case you are wondering, graylisting is a spam protection measure when a recipient email server temporarily blocks an incoming email from an unrecognized address. The sending server can try to send the email again after a delay.
Hard email bounce
A hard email bounce means that the email was not delivered because of a bigger issue, most often the result of sending an email to an invalid or wrong email address.
The most common reasons for a hard bounce are:
-
- Invalid email address
- Non-existent email domain
- The recipient email server has blocked your email
- The email was registered as SPAM
- Low sender reputation
A hard email bounce can sometimes be caused by a strict email server filter.
How a high email bounce rate affects your email campaigns
A high email bounce rate can severely impact the success of your email marketing. It could damage your sender’s reputation and hurt your email deliverability at the same time because the emails you are sending will be sent to the SPAM folder.
If the number of bounced emails stays high the overall effectiveness of your email marketing will suffer. A low mail delivery rate means fewer recipients and potential clients have a chance to open your emails and your open, click-through and conversion rates will all be impacted, resulting in a low ROI.
That is why you would want to keep track of your bounce rate and make sure it is as low as possible.
How to calculate your email bounce rate
Most email service providers measure the bounce rate of your email campaigns, but just in case here is a simple way to know your email bounce rate.
(# of bounces / # of delivered emails) x 100 = your email bounce rate
For example, if you send 100 emails and 5 bounces, you would need to divide the 5 bounced emails by the 100 sent emails and then multiply by 100. In this specific case, you will get a 2% bounce rate.
What is a good email bounce rate?
You should expect a certain number of the emails you send to bounce over the course of an email campaign.
Having a small number of emails bounce is perfectly fine. What you should focus on is keeping the number of bounced emails low. Try to keep your email bounce rate under 2%, which is considered an acceptable bounce rate.
If your bounce rate is noticeably higher, however, for example, 5% or even 10%, then you have a more serious problem that can potentially result in several negative consequences. So, try to keep your bounce rate under the average reported rate.
Industry average email bounce rate
The average rate of bounced emails varies by industry, as well as the day and time of day the email is sent. Email marketing benchmarks by Campaign Monitor, report that the average email bounce rate for all industries is 0.7%.
The Food and Beverage industry reports a bounce rate as low as 0.20% while the Automotive and Aerospace industry has the highest reported bounce rate of 3.80%.
Try to keep your bounce rate in line with your industry average, with the following tips.
How you can lower your email bounce rate
Now that you know why your emails bounce and why it is important to keep them from bouncing here are several tips on how you can reduce your bounce rate.
Here are 12 things you can do to improve your email bounce rate and email delivery.
1. Clean your email list
Nothing lasts forever, that also includes your email lists.
The contact you are emailing might have changed the company they work for or got a new position and that means that the email address that you are trying to reach out to no longer exists. This happens more often than you think, especially now when certain industries report a lower retention rate.
Data decays at a very fast rate, in fact, it is recommended that you clean your email list and your data every 6 months to be on the safe side.
You can use email verification services to help you with this task, which brings us to the next point.
2. Email verification
Verifying your emails lists is easy and a must especially to be sure your email list is up to date. Also, if you are thinking of buying one, which will talk about a bit later.
Depending on your service, there will be an email verifier available you can use to verify your email list quickly.
We have an email verifier available on our platform and also we verify your imported email lists when you upload them in our Email Sequences so you can rest easy that your emails will go where they need to.
3. Remove hard email bounces
If you are sending multiple email campaigns at once, be sure to monitor the number of hard bounces and remove them immediately before you damage your sender’s reputation.
Your email automation service should do this automatically, still just to be on the safe side, it never hurts to double-check if you have set your campaign with a few follow-up messages.
4. Double opt-in forms
Having a double opt-in process is a great way to quickly verify new email addresses and maintain a low bounce rate.
An automated confirmation email effectively guards you against potential spammers, bot accounts and invalid emails. Also, a person can mistype their email, especially on a mobile phone and that means a hard bounce as that email will not exist.
Another way of using a confirmation opt-in is to give the recipients of your email list a choice in what type of content they prefer to get from you. If you rely heavily on content marketing, ask them what kind of emails they would like to receive from you, newsletters, platform updates, articles and special offers even.
Using a permission-based process can improve your email bounce rate and the effectiveness of your email campaign by removing inactive emails. Now lets you focus more on quality instead of quantity.
Email lists with a double opt-in are more likely to actively engage with your brand.
5. Email list segmentation by engagement
Segmenting your email list by engagement, lets you send emails to recipients who have already interacted with your email messages.
This way, you are sure that the bounce rate stays low and it can improve your open and click-through rates as well.
6. Consistent email communication
From the moment you send a welcome email to your email list, you begin to nurture a connection. A frequent and reliable email campaign helps remind the recipients on your email list consistently of your business and raises your brand awareness.
Be careful not to overdo it, as sending emails too often even to an active email list can result in email fatigue and may alert the spam filters. Send your emails over a prolonged period of time.
On the other hand, if your sending schedule is inconsistent and there are large time gaps between emails sent, people may forget about you and report your emails as spam and that will negatively impact your bounce rate.
Regular email communication also helps you better control your bounce rate, by removing inactive and deleted emails as a periodic check-up instead of having to deal with sudden spikes in your bounce rate.
Your email delivery frequency will vary as there is no set rule. It depends on the specifics of your email list, market and recipient preference.
Test your sending frequency and monitor the results. Make changes, based on the data you gather.
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7. Bought email list
There is a heated debate on the topic of buying email lists. While some say that it can be profitable to buy a lead-ready list, you need to ask yourself before committing to the purchase is it worth it, considering the possible negative consequences.
You save time, not having to look for potential leads, but just make sure that you verify the emails because you have no way of knowing if those emails are valid and the only way to know is to do it yourself. Otherwise, you risk putting your domain reputation on the line and risk getting blacklisted in the case that some of them might be a honey trap for spammers.
8. Avoid spam filters
No one likes spam emails in their inbox. Yet we still get them from time to time if they manage to slip through the ever-evolving filtering systems in place. Email services have become very good at catching them.
To avoid having your emails flagged, don’t use all caps in your email, include contact details in your signature, don’t use a lot of graphical elements and images and always include an unsubscribe link.
In addition, pay close attention to the subject line as certain words and characters can be enough to banish your email to the SPAM folder. Here is a great list of stop words you should watch out for when writing your subject line.
Personalizing your subject lines plays an important part in your email bounce and open rates, as it makes your email look more targeted and less generic, which is a typical sign of a spam email campaign.
You can also verify your domain to reduce the chance of your emails being flagged.
9. Use email authentication
Email services like Google, Outlook and Yahoo check the status of your sending domain. A verified domain tells the recipient email server that your domain is valid, and the emails sent from it are safe.
There are three ways of email authentication: SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance).
Authenticating your emails is key to achieving good deliverability rates, as it helps you meet accepted standards put in place by ISPs.
10. Don’t use a free email domain
Regarding the previous point, using a free email domain like Gmail, Outlook, or Yahoo Mail is not recommended as they automatically fail a DMARC check. That means your emails will bounce or will be sent to the junk folder.
Plus using Gmail, Outlook and Yahoo! Mail for sending business-related emails, looks unprofessional honestly.
11. Maintain a high sender reputation
A low sender reputation can indicate that your emails are spam and will likely be blocked from reaching the recipient by the email service provider. That’s why keeping your sender reputation high is important as it directly influences your email delivery rate long term.
Worst case scenario if your sender reputation keeps falling you might get blacklisted and labeled as a spammer. If this happens, if your email is sent to a verified email address you may get a bounce message.
12. Email warm-up
Following up on the previous point, having a high sender reputation is important a lot more than you think.
Say you bought a new domain, set up your email campaigns and want to start sending right away. There you’ll hit a roadblock since new domains are not trusted by email service providers and have a limited sending capacity.
For example, Google limits the number of emails you can send from a new domain to 50 emails per day. Moreover, emails sent from new and very often not authenticated domains run a higher risk of being labeled as spam and bounce back.
Email warm-up is a way to increase your email sender reputation and credibility by sending a small number of emails at first and gradually increasing that number to appear as if a real person is sending those emails.
The email warming-up period depends on the number of emails sent and the rate of email engagement. Depending on these two factors, the process usually lasts a couple of weeks.
Our Email Sequences module has an email warm-up feature coming up relatively soon, which will be great for you if you are a start-up with a new domain but can’t wait to send those emails to new leads.
Email bounce codes
When your email bounces you receive a code message by the recipient server with a three-digit number, describing why the email bounced. The code can tell you if it was a soft or a hard bounce.
Note that different email services can have their own bounce messages as they are customizable and that the number of bounce messages can vary.
There are two types of email bounce codes, traditional and enhanced.
Traditional email bounce code list
A traditional SMTP bounce code is a three-digit code.
| Code | Explanation |
|---|---|
| 421 | Service not available, closing transmission channel |
| 450 | Requested mail action not taken: mailbox unavailable (e.g., mailbox busy) |
| 451 | Requested action aborted: error in processing |
| 452 | Requested action not taken: insufficient system storage |
| 500 | The server could not recognize the command due to a syntax error. |
| 501 | A syntax error was encountered in command arguments. |
| 502 | This command is not implemented. |
| 503 | The server has encountered a bad sequence of commands. |
| 504 | A command parameter is not implemented. |
| 550 | The user’s mailbox was unavailable (such as not found) |
| 551 | The recipient is not local to the server. |
| 552 | The action was aborted due to exceeded storage allocation. |
| 553 | The command was aborted because the mailbox name is invalid. |
| 554 | The transaction failed for some unstated reason. |
Enhanced email bounce list
An enhanced SMTP bounce code consists of a three-digit code, separated by decimal points.
| Bounce Code | Bounce Type | Description |
|---|---|---|
| 4.2.2 | Soft | The email account is over quota |
| 5.0.0 | Hard | The address does not exist |
| 5.1.0 | Hard | Other address status |
| 5.1.1 | Hard | Bad destination mailbox address |
| 5.1.2 | Hard | Bad destination system address |
| 5.1.3 | Hard | Bad destination mailbox address syntax |
| 5.1.4 | Hard | Destination mailbox address ambiguous |
| 5.1.5 | Hard | Destination mailbox address valid |
| 5.1.6 | Hard | Mailbox has moved |
| 5.1.7 | Hard | Bad sender\’s mailbox address syntax |
| 5.1.8 | Hard | Bad sender’s system address |
| 5.2.0 | Soft | Other or undefined mailbox status |
| 5.2.1 | Soft | Mailbox disabled, not accepting messages |
| 5.2.2 | Soft | Mailbox full |
| 5.2.3 | Hard | Message length exceeds administrative limit. |
| 5.2.4 | Hard | Mailing list expansion problem |
| 5.3.0 | Hard | Other or undefined mail system status |
| 5.3.1 | Soft | Mail system full |
| 5.3.2 | Hard | System not accepting network messages |
| 5.3.3 | Hard | System not capable of selected features |
| 5.3.4 | Hard | Message too big for system |
| 5.4.0 | Hard | Other or undefined network or routing status |
| 5.4.1 | Hard | No answer from host |
| 5.4.2 | Hard | Bad connection |
| 5.4.3 | Hard | Routing server failure |
| 5.4.4 | Hard | Unable to route |
| 5.4.5 | Soft | Network congestion |
| 5.4.6 | Hard | Routing loop detected |
| 5.4.7 | Hard | Delivery time expired |
| 5.5.0 | Hard | Other or undefined protocol status |
| 5.5.1 | Hard | Invalid command |
| 5.5.2 | Hard | Syntax error |
| 5.5.3 | Soft | Too many recipients |
| 5.5.4 | Hard | Invalid command arguments |
| 5.5.5 | Hard | Wrong protocol version |
| 5.6.0 | Hard | Other or undefined media error |
| 5.6.1 | Hard | Media not supported |
| 5.6.2 | Hard | Conversion required and prohibited |
| 5.6.3 | Hard | Conversion required but not supported |
| 5.6.4 | Hard | Conversion with loss performed |
| 5.6.5 | Hard | Conversion failed |
| 5.7.0 | Hard | Other or undefined security status |
| 5.7.1 | Hard | Delivery not authorized, message refused |
| 5.7.2 | Hard | Mailing list expansion prohibited |
| 5.7.3 | Hard | Security conversion required but not possible |
| 5.7.4 | Hard | Security features not supported |
| 5.7.5 | Hard | Cryptographic failure |
| 5.7.6 | Hard | Cryptographic algorithm not supported |
| 5.7.7 | Hard | Message integrity failure |
| 9.1.1 | Hard | Hard bounce with no bounce code found. It could be an invalid email or rejected email from your mail server (such as from a sending limit). |
The bounce codes and messages can vary depending on the recipient’s email server. The examples shown in the above tables, taken from ActiveCampaign and Salesforce.
Work on your email bounce rate
While often overlooked, your email bounce rate can dramatically affect the deliverability of your emails. If it’s too high, it can be detrimental to your entire email campaign and you’ll struggle to get the results you want. Although a low rate of bounced emails is sadly inevitable, by doing the things we’ve laid out above you will maintain the quality of your email list and the trust factor of your domain.
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