Mailbox Providers Rely on “Hidden” Engagement Metrics for Email Filtering Decisions

New research from Return Path reveals industry benchmarks for seven key measurements that impact deliverability

NEW YORK--()--Data solutions provider Return Path today released its first ever email engagement benchmark report, The Hidden Metrics of Email Deliverability. The report provides sector-specific results for email marketing metrics including read rate, forward rate, and complaint rate—that collectively reveal a great deal about subscriber engagement and play a role in determining which messages reach the inbox. According to this report, verticals that outperformed all benchmarks saw less email delivered to spam.

“Major mailbox providers like Microsoft, Google, and Yahoo! rely on subscriber engagement signals in addition to sender reputation to filter out unwanted email and deliver more desired emails to the inbox,” said Scott Roth, General Manager, Email Optimization at Return Path. “These are metrics that many marketers are not yet tracking, and can have a major impact on deliverability. But there’s also opportunity for marketers to optimize consumer engagement and improve their marketing campaigns using this data.”

Among the key findings from this report:

  • Only two industries—utilities and services—beat all engagement benchmarks and saw some of the lowest amounts of email delivered to spam.
  • The amount of promotional emails delivered to the spam folder ranged from just 2% (utilities) to 28% (automotive parts/accessories).
  • Verticals with the highest read rate in 2015 were utilities (47%) and distribution/manufacturing (31%). Business/marketing and social/dating companies had the lowest read rate (9%).
  • Most industries saw a flat to slightly declining read rate in the fourth quarter, with just one industry—utilities—experiencing a double-digit drop (-14%).
  • The average deleted before reading rate across all industries remained steady at 9% throughout the year. Industries that exceeded this mark significantly include office supplies (14%), pets (13%), and flowers/gifts (13%)—a sign of poor subscriber engagement and possible indicator of over-mailing.
  • In the fourth quarter of 2015, spam complaints increased by an average of 0.5%, indicating that subscribers may not appreciate the increased volume of promotional emails around the holidays.

Report findings are drawn from more than 3.5 billion commercial emails received in 2015. The report analysis is broken down by sector, allowing marketers to see how their own subscriber engagement stacks up against their industry peers and identify opportunities for improvement—ultimately leading to enhanced deliverability and marketing ROI.

The complete Hidden Metrics of Email Deliverability report can be found here.


Return Path conducted this study using global consumer data consisting of over 5,000 commercial senders, 2.5 million consumer panelists and 3.5 billion commercial email messages received between January 1, 2015 and December 31, 2015. Consumer data is defined as information captured from monitored email accounts controlled by real subscribers to sample user-initiated and engagement based filtering decisions by mailbox providers. Consumer data can uncover behavior-based factors and thresholds that influence inbox placement at large mailbox providers that can’t be identified by non-interactive seeds.

About Return Path

Return Path analyzes the world’s largest collection of email data to show businesses how to stay connected to their audiences, strengthen their customer engagement, and protect their brands from fraud. Our data solutions help analysts understand consumer behavior and market trends. We help mailbox providers and security providers around the world deliver great user experiences and build trust in email by ensuring that wanted messages reach the inbox while spam and abuse don’t. Find out more about Return Path Email Optimization, Email Fraud Protection, and Consumer Insight solutions at


Return Path
Jennifer Ribble, +1-317-315-1412

Release Summary

New research from Return Path reveals industry benchmarks for seven key measurements that impact deliverability.


Return Path
Jennifer Ribble, +1-317-315-1412