Understanding Email Metrics (Part 1)

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As we all know, email delivery is challenging in and of itself. However, once an email leaves your application, server, or mail client, you quickly encounter another obstacle: understanding what actually happens to that message.There are several different metrics that the average company should consider tracking in order to gain useful insight and produce educated business decisions.

In this post, we will cover a subset of the statistics that SendGrid tracks for its users and explain what each means. The metrics featured here are mostly relevant to marketing-focused messages. We will release a follow-up post in the coming days, which will discuss the other metrics available through SendGrid’s advanced analytics engine.


A request is an email sent and is reported in your SendGrid dashboard every time our servers get a “request” from your application or server to send an email to one of your customers.


“Delivered” seems pretty obvious, right? At a fundamental level, a delivery is recorded when a request to send an email results in an email being delivered to the end recipient. However, there is a little more to it. You could consider an email classified as “delivered” to mean that an ISP has accepted the email and said “OK, I’ll take this email off your hands.” However, “delivered” does not necessarily mean that your email is in the recipient’s inbox, and it could even mean that it was delivered to the spam box or completely dropped from their system after being accepted. Lastly, if an email is “delivered” you can be certain that it was not deferred by the ISP (“deferral” will be covered in Part 2 of this post).

Clicks & Unique Clicks

The “Clicks” statistic represents the total number of times your users have clicked on the various links within your emails. “Unique clicks” represents the number of unique individuals that have clicked the links in your emails. So, if a certain customer clicks the same link more than once, it will only be reported once in the “unique clicks” count.

Opens & Unique Opens

The concept explained above regarding clicks also applies to opens. An important thing to keep in mind when evaluating numbers around opens is that many email clients often do not load images by default. Therefore, a customer could potentially open your email, read it, and even click a link, without an open being reported. This is obviously not ideal, but as we advance in our tracking mechanisms, we should be able to gain greater accuracy in instances such as this.


In order to maintain compliance with CAN-SPAM laws, any email that is sent in bulk to a mass audience should include an unsubscribe link. SendGrid provides a “Subscription Tracking” app that automatically adds this link to your emails. When someone clicks that link within their email, they are added to your “unsubscribe” list. The next time you send to the address as part of your regular newsletter list, we will not attempt to send to email addresses that appear on this list. Sending to an address that has unsubscribed from your mailings can be detrimental to your reputation. Typically, transactional emails do not need to include unsubscribe links; however, marketing newsletters should always include one.

Enable Click, Open, and Subscription Tracking in the “My Apps” Section of your SendGrid account

Each of these metrics is important to consider when evaluating the performance of your email campaigns. Overall campaign performance should essentially guide your decisions around customer communications, and a full picture is essential to making smart decisions.

SendGrid customers are able to access all stats from our web interface when logged in as a user at SendGrid.com or through our Event API.

We’d love to hear about the role that email metrics play in your everyday business decisions. How often do you evaluate your email statistics? Once you’ve evaluated, how do you employ the insight you’ve gained? Let us know via email, twitter, facebook, or phone!

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Director, Developer Relations at @SendGrid. Passionate about bringing people together around things they love. I tweet at @TimFalls.

Tim Falls on Twitter

7 thoughts on “Understanding Email Metrics (Part 1)

    • Courtney –

      Thanks for reading. There are some consistencies across all the different email service providers and the way they define the various metrics that their systems track. However, there are also many inconsistencies due to different technologies, capabilities, etc.

      Here are a few resources that you might find helpful:
      – Marketing email metrics defined: http://www.youtube.com/watch?v=BdYssWA55fQ (Stephanie Miller of Return Path & the Email Experience Council)
      – Blog posts on Deliverability.com, within the "metrics" category: http://blog.deliverability.com/metrics/
      – Google Analytics is one tool that does a good job of standardizing metrics across the board, since it is rather agnostic in nature: http://sendgrid.com/blog//how-to-track-your-emails

      I hope this helps. We will keep searching, and if we find any additional resources, we will include them in our upcoming "Email Metrics (part 2)" post or share them via twitter.


      Tim Falls

  1. Hi Tim,

    Great post! Just trying to figure out exactly how you track clicks. With the opens there is an invisible image, but how does it work with the clicks?


  2. Christine –

    As a SendGrid user, if you have "Click Tracking" enabled, we overwrite all links within your emails with a unique URL that our system can track. So, when your customer clicks a link within an email you've sent, it notifies our system to record that click, and then our system recalls the original URL and redirects your customer to the appropriate site/page.

    Let us know if you have any other questions.

    Thanks for reading and joining the conversation!


  3. Pingback: Understanding Email Metrics (Part 2) - SendGrid Blog – Email Delivery. Simplified

  4. Hi Tim great post. Some questions:

    First, you mentioned that "delivered" is an inexact science. What are some ways you can specifically determine delivered? Is it possible to really ever confirm?

    Second, I've always been curious about the inexactness of open stats because of exactly what you said – that many clients don't load images by default. Given this, when you see X number of opens do you assume that you're missing some % of them as a result of clients not loading images? If so, what percentage? Finally and related to this, when you report opens and the user sees that number, is there something communicated to them that says the number might be inexact (some margin of error)?


  5. Matt –

    Thanks for reading and submitting the questions. Here are some thoughts:

    1. You can use "seed" (test) mail accounts and send samples of your emails to these seed accounts. The results are easily observed and can give you an idea of where the emails are landing (ie, inbox / spam / blackhole). SendGrid customers can use our Event API and/or the Email Activity search to see stats on who actually opens / clicks on an email, which confirms that an email was delivered.

    2. It seems that there has probably been some sort of study done on this, but if it's out there, it has escaped us so far. After asking some other folks on our team, no one had a ballpark number to present with any confidence. However, it's a very interesting concept that we think is worth further investigation – perhaps a topic for a future blog post?

    Stay tuned…


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