Definition: Email Bounce Rate

Email Bounce Rate is the percentage of emails sent which weren’t delivered. In general terms – the higher the bounce rate, the worse your email marketing list.


[Disambiguation: If you are looking for the bounce rate which applies to websites/webpages, please go here]


What Does Email Bounce Rate Mean?

When an email bounces it means that the recipient email address has not accepted the email. This can happen for many reasons. Email providers will count all of the bounces that occur and show them as a percentage of all the email addresses that you attempted to contact. This is your bounce rate.

Note: Unfortunately, there doesn’t seem to be a consensus among email platforms for what we should call the total number of attempted emails sent. Some platforms call it “Attempted” and some call it “Sent” but the majority seem to avoid using any word at all. We shall be using ‘attempted’ in the below definition.


Email Bounce Rate Equation

Here is the formula to calculate the bounce rate for emails:


Email Bounce Rate EquationClick to enlarge

Email Bounce Rate = (Bounces ÷ Attempted) x 100


What Does “Bounce” Mean For Emails?

If you send an email directly from your personal email address to an email address that does not exist then you will receive an error message like this one:


Example of an email error message


What the error message looks like will change depending on the email provider of the recipient, as well as the reason for the email not being deliverable. However, this is an example of a bounced email.

If you are sending emails via an email service provider to many recipients at once, they will group all of these bounces so they can report on them. There are two types of bounces that can occur:

Hard Bounces: This type of bounce tells you that you cannot email this address anymore. The problem which ‘bounced’ your email is likely permanent:

  • the email address has been shut down
  • the domain name the email address is using doesn’t exist
  • your email address has been blocked (by the recipient or their email server),

Soft Bounces: This type of bounce can be thought of as being a temporary problem. Common reasons for soft bounces include:

  • The email addresses inbox is full and can’t accept your email
  • Your email was too large for the inbox to accept
  • The recipient’s email server was temporarily down


Keeping Your Email Marketing List Tidy

The size of your email marketing list is often a KPI of a business. Email marketing is one of the most powerful forms of digital marketing, and the size of your email list determines how many people you can contact.

If your emails are not being delivered, however, then there is likely something wrong with your email marketing list. Emails that hard bounce are ones that you cannot contact. Including them on your email marketing list is at best self-deception, and at worst self-destructive.

To understand how well you are doing, you should know how many email addresses you can actually contact. Keeping email addresses on your list which you cannot contact is meaningless.

Worst than that, continually contacting email addresses that bounce can have your domain marked as spam, meaning that even fewer of your emails will actually be delivered. You should periodically “clean” your email marketing list of all hard bounces to stop this from happening.


How To Use Bounce Rate To Optimise Email Marketing

By monitoring the bounce rate of your campaigns you can get a sense of whether your email list is working well or not.

Assuming you ‘clean’ your email marketing list of hard bounces then the number of hard bounces you receive should be going down (and therefore your bounce rate). If it isn’t, this means that your emails are likely being marked as spam. To stop this from happening, you should re-examine the format and subject lines of your emails. Do they sound spammy? You should also make sure that you are only contacting people you definitely have permission to contact.

For soft bounces, the main thing you can do is ensure that your emails aren’t too large. Optimise images by compressing them both in terms of dimensions and file size. Don’t add too many images in the first place either! If you are using code to format your email, keep it to the minimum.

A bad bounce rate is a serious problem for email marketing, so monitor it and keep taking action to push it down.


Email Bounce Rate Benchmark

According to Mailchimp, the average soft bounce rate is 0.58% and the average hard bounce rate is 0.4%. Most email marketing platforms only provide a single figure – meaning the overall bounce rate would be 0.98%.

The best benchmark is always your own previous performance, so you should try to improve your bounce rate from email to email. However, if you are looking for a way to compare yourself to others, having a bounce rate of under 1% is the thing to aim for.

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