How Email Marketing Systems Count Success Differently

Decoding Differences: How Email Marketing Systems Track Performance

Decoding Differences: How Email Marketing Systems Track Performance

Key Takeaways:

Understand how different email systems calculate metrics like open rates.

Grasp how plain text and HTML email format can impact your open rates.

Discover the importance of comparing a variety of email metrics when determining the success of a campaign.

At first glance, email marketing systems might appear to be the same. When it comes to measuring email analytics, however, it’s clear that each email system tracks things differently. Let’s take a moment to compare how Constant Contact and Klaviyo measure performance, then contrast how a few other popular email systems measure performance. We’ll also highlight some tracking differences between plain text and HTML email to help inform which one you use for your business. 

Constant Contact vs. Klaviyo

When it comes to email marketing, understanding how your chosen platform tracks and calculates open rates is crucial for interpreting your campaign’s success accurately. Constant Contact and Klaviyo, two popular email marketing systems, employ distinctly different methods for tracking open rates, which can significantly influence the metrics reported.

How Constant Contact Measures Success

Constant Contact uses a traditional approach by inserting a small, invisible image — known as a web beacon or tracking pixel — into the HTML code of emails. When a recipient opens the email, their email client requests the image from Constant Contact’s server. This request allows Constant Contact to register the email as opened. However, this method has a limitation: if the recipient has disabled images in their email client, the open may not be recorded, potentially underreporting the open rate.

Klaviyo’s Advanced Tracking Technique

Klaviyo* goes beyond tracking pixels to provide a broader capture of engagement metrics. It takes a more sophisticated approach known as “email rendering” to track opens. This technique doesn’t solely rely on image downloads but detects when the email content is rendered or displayed in the recipient’s email client. The advantage of this method is that it’s more accurate since it can track opens even if images are blocked or disabled by the recipient.

Comparative Insights on Accuracy and Reporting

There are three key differences in how Constant Contact and Klaviyo calculate open rates:

  1. Tracking Basis
    Constant Contact relies on image downloads, whereas Klaviyo uses email rendering detection.
  2. Accuracy
    Klaviyo’s method tends to be more accurate, as it can still track opens when images are blocked, unlike Constant Contact.
  3. Reporting Consistency
    Due to differing methodologies, the open rate metrics reported by Constant Contact and Klaviyo for the same email campaign can vary. Klaviyo might show higher open rates due to its ability to capture more open instances.

Mailchimp and Salesforce

Two other popular email systems we’ve seen some clients use are Mailchimp and Salesforce. Here’s a brief glimpse of how each platform deals with open and click rate metrics.   


This platform calculates the open rate by using tracking pixels to count how often the image loads for your delivered campaigns. Mailchimp refers to this as an open tracking feature. Unfortunately, this feature doesn’t produce accurate results when an email client chooses not to display images. This feature will only work if you ask clients to add you to their approved sender list or click the “display images” option when opening emails from your brand. As for click rates, Mailchimp can track this metric and display it on the Reports page within the platform. 


Like Mailchimp, Salesforce can calculate open rates via pixel tracking, but this metric’s accuracy is affected if the email recipient turns off image loading. The platform also has the capability to track click rates, a metric which shows up as part of the Click-Through Rate report. It even has a heatmap key feature that uses color coding to show you where your click traffic is coming from geographically. 

Weighing the Differences Between Plain Text and HTML Email 

Platform variances aren’t the only things to consider with email analytics. The format of your emails also plays a role in analytics and reporting. Plain text and HTML emails vary in what you can and can’t track. 


These emails offer extensive tracking capabilities, allowing you to measure open rates, click rates, engagement metrics, and gather detailed information about the recipients’ devices and email clients. However, the effectiveness of open rate tracking is limited by the recipient’s email client settings, such as image blocking. It turns out that HTML emails are more likely to fall prey to spam filters than plain text emails, due to their image-centric format. 

Plain Text 

With plain text emails, you can track click rates, replies, and delivery rates. However, you can’t monitor open rates or gather detailed engagement metrics and device information. One strength of plain text emails is that they are less likely to get blocked by image blockers than HTMLs, since they are text-only. 

“Don’t rely on open rates to gauge the success of your email campaigns. Consider these metrics alongside other indicators such as click-through rates and conversion rates to get a comprehensive view of a campaign’s effectiveness.”

– Technology Therapy® Group

Get the Big Picture with Your Email Metrics

As we’ve seen, not all open rates are calculated with the same degree of accuracy. Whether you’re using an email system with email rendering, like Klaviyo, or one that has an image blocker, your email system calculates open rates in a unique way. And some systems consider an email “open” even if it automatically shows up in the recipient’s preview pane by default. This can cause two systems to generate different open rates for the same campaign.

It’s crucial for marketers to understand these differences, especially when switching platforms. For instance, if you’re moving from Constant Contact to Klaviyo, you might see a change in your open rates or click rates based on how each platform tracks data. 

This variance underscores the importance of not solely relying on open rates to gauge the success of email campaigns. Instead, consider these metrics alongside other indicators such as click-through rates and conversion rates to get a comprehensive view of a campaign’s effectiveness.

Experience the Klaviyo Difference

Its open rate reporting accuracy and advanced tracking features are two of the top things we love about Klaviyo. Try it out for free to see why we recommend it to all our TTG clients!*

*DISCLAIMER: Links included in this article might be affiliate links. If you purchase a product or service with the links that we provide, TTG may receive a small commission. There is no additional charge to you!

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