How to Unlock the Hidden Metrics of Email Deliverability

If you’re an email marketer, you are likely familiar with certain metrics that can be great indicators of a campaign’s performance: open rate, click-through rate, conversion rate; perhaps the unsubscribe rate as well. But as engagement is more critical than ever in order to reach the inbox, there are other metrics that mailbox providers track that you might not have considered. The Hidden Metrics of Email Deliverability: 2016 Industry Benchmarks for 7 Key Measurements examines these.

What are these 7 mysterious measurements?

  1. Spam placement rate, or the percentage of emails delivered to the spam folder as opposed to the inbox.
  2. Read rate, or the percentage of emails marked as “read.” This is more accurate than open rate because it accounts for all emails viewed, regardless of image rendering.
  3. Deleted before reading rate, or the percentage of emails that were deleted before they were read. You can also think of this as the “ignore rate.”
  4. Reply rate, or the percentage of replies to your email. Replies to your emails are generally a strong signal of positive engagement.
  5. Forward rate, or the percentage of your email was forwarded to other people. Like the reply rate, forwards are also a big indicator of engagement.
  6. Complaint rate, or the percentage of “report spam/junk” complaints that your subscribers reported.
  7. “This Is Not Spam” rate, or the percentage of emails that your subscribers marked as “this is not spam” or “not junk” that had originally landed in the spam folder.

The Findings

  • Compared to 2015, overall spam folder placement rose in 2016.
  • All industries saw an increase in read rate compared to 2015.
  • Compared to the year prior, each industry saw increases in their deleted without reading rates, ranging from 2 percent to 5 percent. This shows that not only did positive engagement increase in 2016 (via read rates), but negative engagement did as well.
  • The average reply rate more than doubled between 2015 and 2016.
  • Overall, forwards saw a slight increase in 2016.
  • Total complaints slightly increased, but the year over year change varied by industry.
  • Every industry saw “this is not spam” rates rise in 2016.

Key Takeaways
Sender reputation is not the only element that marketers need to pay attention to. Despite some fluctuations by industry, all of the metrics outlined above increased from 2015 to 2016. Mailbox providers recognize this and are increasingly taking subscriber engagement into consideration when making filtering decisions.

It’s up to marketers to not only increase positive engagement (read rates, forwards, replies, “this is not spam” hits), but also to reduce negative engagement (spam complaints, messages deleted without reading) in order to reach the inbox. But how does one accomplish this?

  • Test your campaigns. Instead of making choices about the creative or subject line that you think may resonate better with your subscribers, make data-driven decisions by conducting A/B tests to small samples of your list first.
  • Segment, segment, segment. The days of batch and blast email are over. Different subscribers have different preferences and tastes. Don’t treat them all alike; divide them into different segments and tailor your campaigns so that they are targeted to each individual group. It may be a little more work upfront, but you might just increase your chances of resonating with your subscribers, making them more likely to engage.
  • No engagement is bad engagement. Sure, maybe you have a handful of folks who don’t delete your mail or mark it as spam—but they may not be reading your messages or clicking through on them either. While some may see this kind of subscriber as “neutral,” the reality is that they could be hurting you by acting as dead weight on your list. If subscribers are ignoring your mail, chances are they don’t want it, and you shouldn’t be mailing to them. Be sure to validate any incoming email addresses you acquire and perform routine list hygiene to remove inactive addresses from your list. This will avoid you sending to unknown users and spam traps.

minute read

Popular stories



BriteVerify email verification ensures that an email address actually exists in real-time


The #1 global data quality tool used by thousands of Salesforce admins


Insights and deliverability guidance from the only all-in-one email marketing solution

GridBuddy Cloud

Transform how you interact with your data through the versatility of grids.

Return Path

World-class deliverability applications to optimize email marketing programs

Trust Assessments

A revolutionary new solution for assessing Salesforce data quality


Validity for Email

Increase inbox placement and maximize subscriber reach with clean and actionable data

Validity for Data Management

Simplify data management with solutions that improve data quality and increase CRM adoption

Validity for Sales Productivity

Give your sales team back hours per day with tools designed to increase productivity and mitigate pipeline risks in real-time