Black Friday email messages with free shipping offers had the highest average conversion rate last year, and Cyber Monday messages with percent-off offers had the highest average conversion rate, according to recent research from Yes Marketing.

The report was based on Yes Marketing data from more than 8 billion emails sent by brands in 4Q17. The researchers compared 2017 data for Black Friday and Cyber Monday messages with 2016 data, as well as with business-as-usual (BAU) emails.

Black Friday campaigns that included free shipping offers had a significantly higher average conversion rate (14.7%) compared with campaigns that included other offer types (dollar-off, percent-off, buy-one…).

Black Friday campaigns that included offers had lower average open, unique click, and click-to-open rates compared with brand campaigns that did not include offers.