New Research from Return Path Demonstrates Link Between Subscriber Engagement and Reduced Spam Placement


Fourth annual report reveals industry benchmarks for key metrics that impact deliverability

Here are some of the key points and trends from the report, The 2019 Hidden Metrics of Deliverability. This study looked at mail from the top webmail providers: Gmail, Microsoft (Hotmail,, etc.) and Verizon (Yahoo, AOL), and the deliverability and engagement metrics not typically seen in an email marketer’s dashboard.

  • Good news for marketers as mail is being delivered to the spam folder less often. There are likely a number of reasons for this boost: thanks to advances in AI and ML, spam filters are better today at identifying spam and phishing messages, as well as wanted email; Recent legislation like GDPR forced many email marketers to adopt new practices on consent and data retention that resulted in higher quality email lists.
  • As a result, read rates, or open rates, are on the rise. With more email reaching the inbox and being seen, subscribers are opening more emails (2% increase YoY).
  • Emails are reaching the inbox more often doesn’t mean that all them of them are being opened. As a result, we also saw more people ignoring these campaigns by deleting without reading them (4% increase YoY).
  • Fewer people are replying to emails as well. While the data show the intention of the reply, typically reasons include unsubscribing from an email, or requesting customer service or support. Part of this trend could be a result of email providers like Gmail making it easier for users to unsubscribe from unwanted email or marketers proactively cleaning lists. While this metric isn’t necessarily good or bad, replying to emails can often act as a signal that the email is important and ensure future delivery to the inbox. Regardless, marketers should avoid sending from an email that does not accept replies or isn’t monitored.
Trouble on the horizon?
  • Emails marked as spam (i.e. complaints) increased 129% YoY. The most logical explanation for this is due to the increase in emails being delivered to the inbox. As visibility increases complaints, similar to read rates, also increase. While the increase didn’t impact placement in 2018, marketers should keep a close eye on their complaint rates in 2019.
  • Fewer emails are also being marked as “Not Spam” decreasing from 1.77% in 2017 to only .02% in 2018. This isn’t necessarily a bad thing. It could point to smarter spam filters. As previously mentioned, less email was delivered to the spam folder in 2018, resulting in subscribers needing to override these decisions less. But one thing is certain: if complaints continue to rise in 2019 resulting in more deliverability issues, marketers will want to keep a close eye on their “not spam” rates, as it’s one of the strongest signals to spam filters that they made a mistake.


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