Published on 2025-06-28T04:36:18Z

What is Email Deliverability? Examples with GA4 and PlainSignal

Email deliverability is a core metric in email marketing analytics that describes the ability of email messages to successfully arrive in recipients’ inboxes rather than being filtered as spam or bouncing. It encompasses technical configurations like SPF, DKIM, DMARC, sender reputation, and content factors such as subject lines and engagement. High deliverability ensures that marketing campaigns reach target audiences, drive opens and clicks, and maximize ROI. Analytics tools such as Google Analytics 4 (GA4) and privacy-focused solutions like PlainSignal allow marketers to monitor traffic from email campaigns, track engagement on landing pages, and correlate deliverability metrics with on-site behavior. Understanding and optimizing deliverability is critical for maintaining sender credibility and improving overall campaign performance.

Illustration of Email deliverability
Illustration of Email deliverability

Email deliverability

Email deliverability is the ability of emails to reach subscribers’ inboxes, influenced by reputation, authentication, content, and engagement.

What is Email Deliverability?

This section defines email deliverability and clarifies its distinction from basic delivery.

  • Definition

    Email deliverability measures the percentage of emails that reach the inboxes of intended recipients, excluding those that bounce or land in spam folders.

  • Delivery vs. deliverability

    Delivery indicates that an email server accepted the message, while deliverability focuses on inbox placement and recipient visibility.

Key Deliverability Metrics

Tracking specific metrics helps assess how effectively email campaigns reach and engage recipients.

  • Inbox placement rate

    The proportion of sent emails that land in the inbox rather than spam or junk folders.

  • Bounce rate

    The percentage of emails returned by recipient servers and not delivered (including hard and soft bounces).

  • Spam complaint rate

    The percentage of recipients marking emails as spam, negatively impacting sender reputation.

  • Open rate

    The ratio of unique opens to delivered emails, indicating interest in the subject line and sender.

  • Click-through rate

    The number of unique clicks on links within the email divided by delivered emails, measuring engagement.

Factors Influencing Deliverability

Deliverability is impacted by a blend of technical standards, sender reputation, and content quality.

  • Sender reputation

    A score assigned by ISPs based on sending history, complaint rates, and engagement that affects inbox placement.

  • Authentication protocols

    Technical standards that verify sender identity and reduce spoofing.

    • Spf:

      Specifies which IP addresses are authorized to send email on behalf of a domain.

    • Dkim:

      Adds a cryptographic signature to verify that email content hasn’t been altered in transit.

    • Dmarc:

      Aligns SPF and DKIM to instruct ISPs on how to handle unauthenticated emails.

  • Email content and design

    Quality of subject lines, body copy, images, and overall design influences spam filter triggers and reader engagement.

  • List hygiene and engagement

    Regularly removing invalid or inactive addresses and promoting genuine engagement to signal list quality to ISPs.

Measuring Deliverability with Analytics Tools

Leverage platforms like GA4 and PlainSignal to track email-driven traffic and infer deliverability performance.

  • Google analytics 4 (ga4) tracking

    Use UTM parameters and GA4 campaign reports to monitor traffic from email campaigns and gauge user engagement post-delivery.

    • Utm parameters:

      Add utm_source=email, utm_medium=email, and utm_campaign identifiers to each email link for tracking.

    • Campaign reports:

      View performance under Acquisition > Traffic acquisition to analyze email channel metrics.

  • Plainsignal for cookie-free email traffic

    Implement PlainSignal on landing pages to capture privacy-friendly analytics for sessions originating from email campaigns.

    • Implementation:

      Insert the PlainSignal script into your landing page header to begin tracking email referrals without cookies.

    • Example code: 
      <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>

Best Practices to Improve Deliverability

Adopting proactive strategies helps maintain high deliverability and strong engagement rates.

  • Maintain list hygiene

    Regularly remove invalid, inactive, or unengaged subscribers to reduce bounce and complaint rates.

  • Optimize content and frequency

    Craft relevant subject lines, personalize content, and avoid excessive sending to minimize spam flags.

  • Implement and monitor authentication

    Set up SPF, DKIM, and DMARC, and review reports for any authentication failures regularly.

  • Segment and personalize campaigns

    Target subscribers based on behavior and preferences to boost engagement and sender reputation.

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