Definition:
A bounce is a term used in web analytics and email marketing with different meanings. In Google Analytics 4 (GA4), it corresponds to a session that does not meet the engagement criteria. In email marketing, it occurs when an email cannot be delivered to its recipient.
On the web, it helps analyse visitor behaviour; in email, it identifies a delivery problem. A bounced message does not indicate that the recipient has lost interest, since they have not been able to receive it.
Bounces in email delivery
In email marketing, a bounced email is one that could not be delivered. The reason reported by the server allows two main types to be distinguished:
- Hard bounce: indicates a delivery failure considered permanent, such as a non-existent address or a permanent block by the receiving server. Sending platforms usually exclude these addresses from subsequent campaigns.
- Soft bounce: indicates a delivery problem considered temporary, such as a full mailbox, an unavailable server or a message that is too large. The platform may retry delivery. If the problem persists, it may suspend sending to that address.
Classification and retries depend on the provider and the server response. Not all rejections have the same cause or should be handled in the same way.
Bounces on the web
In web analytics, bounces help interpret user behaviour on a website.
In GA4, a session is considered engaged when it lasts longer than 10 seconds with the default setting, records a key event or includes at least two page or screen views. If it meets none of these criteria, it is counted as a bounce. The time threshold can be configured.
Visiting a single page does not necessarily imply a bounce. The bounce rate expresses the percentage of non-engaged sessions out of all sessions.
A high rate may be related to less relevant content, navigation difficulties or technical problems. However, it does not by itself prove that any of these problems exist. Its interpretation must take account of visitor intent, page type and measurement settings.
Strategies to reduce bounces
The measures depend on the context: on the web, the aim is to facilitate useful engagement; in email marketing, it is to reduce the failures that prevent messages from being delivered.
How to reduce bounces on the web
Content and the browsing experience are two areas that can be reviewed:
- Content optimisation: maintain information relevant to the visits each page receives, with clear headlines and calls to action that match its purpose.
- Design and navigation improvements: make information easy to access, adapt the site to different devices and reduce loading times that hinder its use.
These improvements should be assessed alongside the actions that matter on each page. Reducing the bounce figure does not, by itself, constitute an improvement in the outcome.
How to reduce bounces in sent emails
Reviewing lists and delivery errors helps identify specific measures:
- Regular mailing list cleaning: correct typing errors and exclude addresses with confirmed permanent failures from further sending. A lack of opens does not by itself prove that an address is invalid.
- Review of temporary failures: check rejection reasons, message size and the authentication requirements of the recipient. Retries should be adapted to the cause and how the platform works.
Segmentation and personalisation can improve message relevance, but they do not, by themselves, resolve a full mailbox, a non-existent address or an authentication problem.