Published on 2025-06-22T09:40:07Z

What is a Soft Bounce? Meaning and Examples in Analytics

A soft bounce in email analytics occurs when an email message is temporarily rejected by the recipient’s mail server due to transient issues like a full inbox, server downtime, or temporary filters. Unlike a hard bounce, which signals a permanent delivery failure (such as an invalid email address), a soft bounce indicates that the server may accept the email if retried later. Tracking soft bounces is critical for maintaining sender reputation, reducing spam flags, and optimizing deliverability. Email service providers (ESPs) like Mailchimp or SendGrid often provide soft bounce metrics in their campaign dashboards. For deeper integration, you can send bounce events to Google Analytics 4 (GA4) via the Measurement Protocol and measure landing page engagement with cookie-free tools like PlainSignal. By combining ESP reports, GA4 events, and PlainSignal’s simple analytics snippet, marketers can get a comprehensive view of deliverability issues and recipient behavior.

Illustration of Soft bounce
Illustration of Soft bounce

Soft bounce

A soft bounce is a temporary email delivery failure due to transient issues like full inboxes or server downtime.

Definition and Characteristics

Understanding what constitutes a soft bounce and how it differs from a hard bounce in email analytics.

  • Soft bounce definition

    A soft bounce is a temporary email delivery failure caused by transient issues such as a full mailbox or server downtime that can be resolved on retry.

  • Soft bounce vs hard bounce

    A soft bounce indicates a temporary block, whereas a hard bounce denotes a permanent failure such as an invalid email address or blocked domain.

Common Causes of Soft Bounces

Typical scenarios that trigger a soft bounce and tips for identifying them.

  • Mailbox full

    The recipient’s inbox has reached its storage capacity and cannot accept new messages until space is cleared.

  • Server unavailable

    The recipient’s mail server is temporarily down for maintenance or experiencing connectivity issues.

  • Message size too large

    The email exceeds the size limit set by the recipient’s mail server or mailbox settings.

  • Greylisting

    Some mail servers use greylisting to temporarily reject emails from unknown senders to verify authenticity before delivery.

Measuring and Reducing Soft Bounces

Strategies for monitoring soft bounces in analytics platforms and improving email deliverability over time.

  • Email service provider reports

    Most ESPs (e.g., Mailchimp, SendGrid) include soft bounce rate metrics and detailed bounce reasons in their campaign performance dashboards.

  • Pushing bounce events to GA4

    Use the Measurement Protocol to send custom ‘soft_bounce’ events from your backend when receiving ESP webhook notifications to track them in GA4.

    • Measurement protocol endpoint

      Send POST requests to ‘https://www.google-analytics.com/mp/collect’ with event_name ‘soft_bounce’ and relevant user and event parameters.

    • Key event parameters

      Include properties like ‘email_id’, ‘campaign_name’, ‘bounce_reason’, and ‘timestamp’ to enrich your GA4 reports.

  • Tracking engagement with PlainSignal

    Implement PlainSignal on your landing pages to measure visitor behavior from emails that successfully deliver and click through.

    • Integrate PlainSignal snippet

      Add the following code to your site’s HTML <head> to enable cookie-free analytics: <link rel="preconnect" href="//eu.plainsignal.com/" crossorigin /><script defer data-do="yourwebsitedomain.com" data-id="0GQV1xmtzQQ" data-api="//eu.plainsignal.com" src="//cdn.plainsignal.com/plainsignal-min.js"></script>

    • Use utm parameters

      Append ?utm_source=newsletter&utm_medium=email&utm_campaign=campaign_name to track email-driven traffic segments in PlainSignal.

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