64% of retailers’ emails were opened on a mobile device in the third quarter—13% on tablets and 51% on smartphones—according to the new Experian Marketing Service “Quarterly Benchmark Report.” That’s up from 61% of retailers during the same period in 2015—11% on tablets and 50% on smartphones.

There’s a strong negative correlation between consumers opening retailers’ emails on mobile devices and click rates, as consumers on mobile devices are less likely to click on links within an email, the report finds. Across all industries, total clicks have declined year over year for each of the past four quarters. Within retail, the click rate fell to 2.7% during the third quarter from 2.9% a year earlier.

The report finds that retailers’ email volumes continue to rise; retailers sent 16.3% more emails in the third quarter than they did a year earlier. And that’s on top of a 27.6% jump in email volume in 2015’s third quarter. Those trends are likely to continue in the fourth quarter as data from digital marketing vendor eDataSource suggests that email marketing volumes have significantly risen this holiday season.

Even so, that volume increase hasn’t hurt retailers’ unsubscribe rate, which fell slightly to 0.09% from 0.1%. That may be because retailers like Amazon.com Inc., No. 1 in the Internet Retailer 2016 Top 500 Guide, are increasingly focused on segmenting their customer base according to what customers have bought and looked at on their sites and apps, and then delivering email messages tailored to their specific interests and preferences.

Experian also notes that retailers’ unique open rates—which is a measure of the number of unique subscribers who have opened a retailer’s message—fell to 14.6% from 16.6% a year earlier. But even though the overall unique open rate was down, roughly half the retailers that Experian examined in the report had statistically significant increases in their click rates.

Consumers like to hear from retailers via email, according to another survey from marketing technology Zeta Global—which rebranded from Zeta Interactive in October—and the Relevancy Group. The survey of 1,000 consumers, finds that 93% say email is their preferred communication.

And on some of the largest online shopping days of the year, namely Black Friday and Cyber Monday, more than half of all email clicks took place on mobile devices.