The report was based on 2015 Cyber Monday data from more than 400 US retailers as well as data from 2011 - 2014.
The hour between 7:00 AM and 8:00 AM ET was the busiest time for sending Cyber Monday emails, with 11% of retailers messaging consumers during that period.
There was also a flurry of emails sent between 4:00 PM and 6:00 PM ET as retailers tried to entice shoppers with last-minute offers.
A number of the retailers examined sent emails between 12:00 PM and 2 PM ET, a trend that Bronto had not seen in previous years.
More than half (52%) of the retailers examined sent more than one email on Cyber Monday this year.
Ayaz Nanji is an independent digital strategist and a co-founder of ICW Content, a marketing agency specializing in content creation for brands and businesses. He is also a research writer for MarketingProfs. He has worked for Google/YouTube, the Travel Channel, AOL, and the New York Times.
LinkedIn: Ayaz Nanji