Email bounce is the failure to deliver a message, mostly related to server or spam issues.
Depending on the reason why the email couldn’t be delivered, there are two categories of email bounces:
- Hard bounces happen due to the permanent reasons why an email cannot be delivered, e.g., an invalid recipient’s email address.
- A soft bounce indicates a temporary delivery issue, e.g., the recipient email server is down, the mailbox is full, or the message is too large.
Bounce rate represents the percentage of emails in your campaign that didn't reach the recipients because they were returned by their mail servers.
This is one of the key metrics you should track in your email campaigns along with open, clickthrough, and response rates, as well as the most common deliverability issues.
It’s recommended to keep the number of bounced emails below 5% by regularly removing the bounced emails from your sending list.