Delivery Rate, Open Rate, Click-Through-Rate et al. Rather variable in accuracy individually, but powerful assets when used in combination (and their individual limitations understood). But are they enough..?


Then vs Now

The traditional suite of metrics available to the email marketer is numerous, but sadly not as numerous as the variety of problems that can befall campaign success. This leaves glaring gaps in the understanding of campaign performance, forcing a large amount of trial and error. The problem with trial and error in email marketing is the damage it can do to your reputation, which can take considerable time and effort to repair.

Fortunately, new methods of measurement occasionally surface to attempt to provide the missing picture, and today we will be looking at the Deliverability (or Inbox-Placement) metric.


Key Metrics recap: at-a-glance definitions
  • Delivery Rate The total number of emails sent minus the hard and soft bounces (the total 'delivered'), as a percentage of the total sent. Reliable, but often misrepresented as the total deliverd to the inbox, which it is not.
  • Deliverability Rate (or Inbox-Placement rate) The number of emails that reach their intended inboxes i.e. not lost to spam folders or silently blocked/discarded, as a percentage of the total 'delivered'. Cannot be directly measured, only modelled.
  • Open Rate The number of emails opened (only those that are trackable), as a percentage of the total 'delivered'. Given the limitations in tracking 'opens', this can result in a very inaccurate metric (good article on Open Rate inaccuracies).
  • Click-Through-Rate The number of unique recipients who have clicked a link in your email as a percentage of the total 'delivered'. Can also be measured as the number of unique recipients who have clicked a link in your email as a percentage of the total trackable emails 'opened', but this adds the uncertainty of the Open Rate to the measurement.
  • Clicks The actual number of clicks resulting from a campaign and, along with the total number of emails sent, the only non-disputable figure.

There are additional, finer-tuned metrics such as Click-to-Open, but since they are mostly based on the above, we will focus on the more common ones for simplicity of demonstration.

Real-world Scenarios

Let's take a look at a typical 2-month run of weekly campaigns, set to highlight several common performance issues. First we will attempt to interpret the data with the traditionally-available metrics, then with the addition of the Deliverability Rate. Figures are based on an approximate mailing-list of 50,000 contacts and fairly typical bounce/open/click-through rates:



So can we explain the drop in clicks for weeks 2, 4 and 6?

  • Week 2 "There is a drop in open rate, click-through-rate and clicks. Perhaps the subject line wasn't enticing enough or perhaps less emails are getting through? Is the content itself an issue?"
  • Week 4 "There is a considerable drop in open rate, click-through-rate and clicks. Could it be the same issue(s) as in week 2?"
  • Week 6 "There is a slight drop in open rate, click-through-rate and clicks. Maybe it's just an 'off' week?"

*Modelled by SendForensics as Deliverability Score

The missing inbox placement information can make all the difference:

  • Week 2 Turns out it was a deliverability issue that caused the drop in the number of emails reaching their target inboxes. A pre-emptive deliverability check can prevent this happening again.
  • Week 4 Both the delivery and deliverability rates are unchanged, so the most likely explanation is that the content on offer is just not enticing enough!
  • Week 6 The deliverability rate has dropped noticeably, caused by the blacklisting of your primary sending domain from the week before. Remember those new contacts you imported last week that contained a lot of unvalidated addresses? That send resulted in a number of spam-complaints and bounce-backs from these unvalidated addresses - better sanitise your list before next week's campaign.


There are many other scenarios possible, but I hope this brief breakdown of the analytical process behind a few simple campaign trends can illustrate the benefits of multiple metrics. It's true that looking at certain metrics for a standalone campaign can be individually very misleading, but over time, their combined use can be a very powerful analytical tool. 

Deliverability Metrics & Reporting at SendForensics:
Accessible Deliverability Metrics

Calculate your Deliverability score for all your campaigns and optimise BEFORE you send. Download your modelled inbox-placement rate over time as ready-made graphs for reporting and presentation, or in Excel and CSV formats for combination with your other campaign data OR pull in your live campaign data directly alongside using our ready-made set of ESP plugins.