Some 24% of email messages sent by brands in the second quarter of 2016 never made it to subscribers' main inboxes, according to recent research from Return Path.

To determine its deliverability benchmarks, Return Path looked at 2Q15-2Q16 data from its Consumer Network, which tracks the behavior of certain consumers who use AOL, Gmail, Outlook.com, and Yahoo as their email service.

The researchers also examined data from test addresses that Return Path maintains with hundreds of mailbox providers around the world.

The inbox placement rate (e.g., the share of emails sent by brands that were successfully delivered to subscribers) was 76% globally in 2Q16, down from 81% in 2Q15; and some 18% of emails went missing and 7% ended up in spam folders (the total does not equal 100% because of rounding):

The inbox placement rate in the United States was lower than the global average in 2Q16, with only 69% of brand messages reaching consumers:

About the research: The report was based on 2Q15-2Q16 data from Return Path's Consumer Network as well as data from global test addresses.