Bounce rate is the percentage of sent emails that could not be delivered to the recipient's mail server. It is calculated by dividing the number of bounced emails by the total number of emails sent, then multiplying the result by 100.
For example, if 100 emails are sent and 5 cannot be delivered, the bounce rate is 5%.
Types of Email Bounces
There are two main types of email bounces: hard bounces and soft bounces.
Hard Bounce
A hard bounce occurs when an email cannot be delivered due to a permanent issue. Common causes include an invalid, nonexistent, or deactivated email address.
Soft Bounce
A soft bounce occurs when an email cannot be delivered due to a temporary issue. Common causes include a full recipient inbox, a temporary server issue, or a message that exceeds the recipient server's limits.
Why Is Bounce Rate Important?
Bounce rate helps indicate the quality and deliverability of an email list. A high bounce rate can indicate that a list contains a significant number of invalid or undeliverable addresses.
Repeatedly sending emails to addresses that cannot receive messages can also affect sender reputation and email deliverability .
Monitoring bounce rate helps identify email list quality issues and determine when addresses should be reviewed or removed from future campaigns.