Email marketing may not be flashy, but the channel drove a significant share of e-commerce orders over the holiday weekend and today.

25.1% of e-commerce transactions on Friday stemmed from shoppers clicking from emails, according to report by marketing platform vendor Custora. Another report, by Adobe Systems Inc.’s Adobe Digital Index, finds email marketing accounted for more than 15% of sales referrals between Thanksgiving and Sunday and the number of sales that resulted from shoppers clicking from an email and buying jumped 25% over the same period a year ago.

Custora’s report is based on data from roughly 500 million shoppers’ visits to more than 200 online retail websites; Adobe’s report is based on data from 150 million visits to 4,500 retail websites.

Email played a significant role over the weekend, particularly on Friday and Monday, because consumers are conditioned to look for and respond to limited-time offers they see in their inboxes, says Netta Kivilis, Custora’s head of marketing.

“Email is where retailers can focus on customer retention rather than customer acquisition,” she says. “A lot of retailers we work with are getting extremely sophisticated in how they reach out to the consumers they know about by segmenting their email lists, personalizing offers and sending different promotions to different customers.”

Email’s growth should also be viewed in concert with the sharp rise in mobile commerce, says Tamara Gaffney, principal analyst, Adobe Digital Index. 53% of shopping visits stemmed from consumers on mobile devices between Thanksgiving and Sunday, Adobe finds, and 32% of online purchases were made on a mobile device.

“Email and mobile traffic and sales growth are linked,” she says. “Consumers have had several years to get comfortable with mobile shopping. It’s clear that they’re there now, which means they have no problem clicking from their emails to a retailer’s site on their phone and then clicking and buying—particularly when they know that the offers they find in their inbox are only available for a limited time, as they were over the weekend and today.”

While email helped drive a significant share of sales, social media did not, at least not when examined based on last-click attribution. That’s despite many retailers, including Target Corp., significantly boosting their social media ad budgets. Over the weekend retailers, on average, increased their Facebook ad spending 91% year over year, according to a report by advertising vendor Nanigans. Only around 2% of retailers’ sales stemmed from shoppers clicking from social networks, which is roughly the same percentage for any other day during the year, Adobe says. Custora’s report suggests that social media referral sales rose to 1.7% from its typical 1% on Black Friday.

Facebook, Instagram, Pinterest and other social networks have spent much of the past year trying to remake their platforms—and their ad units in particular—into direct response channels, however, that shift is still a work in progress, Kivilis says.

“No one seems to have cracked the nut to drive significant e-commerce transactions from social,” she says.

However, more consumers than ever discussed shopping over the weekend. Social buzz, which examines how many consumers posted about retailers and Black Friday or related terms, rose about 25%, the Adobe report finds.

And those discussions are important, Gaffney says. She points to the game Pie Face, which unexpectedly was one of the best-selling items over the weekend. The game, which is won when a mechanical arm throws whipped cream in a player’s face, has led to several viral videos of consumers playing the game. Some of those videos have been viewed millions of times, which has helped drive sales of the game—even if those aren’t direct clicks to buy.

“Social media is still a really small channel in terms of direct sales,” Gaffney says. “But it plays a big factor in determining what is going on, what people want. It can create demand for some toy no one has heard of before.”

Retailers can also leverage social media to promote their brands and help consumers learn about products that they stock. For instance, REI, No. 72 in the Internet Retailer 2015 Top 500 Guide, closed its stores on Black Friday to encourage shoppers to be active outside. Promoting the campaign with the hashtag #OptOutside helped the retailer attract more than 50,000 mentions over the past week on social networks tracked by Salesforce.com Inc. That ranked 6th among the large brands tracked by the vendor. “The campaign worked because it stayed true to who REI is,” says Shelly Bransten,senior vice president, retail and consumer products industry solutions.

No retailer generated more mentions than Kohl’s Corp., No. 22 in the Top 500 Guide. For the second straight year the retailer ran a sweepstakes for a $500 gift card on Twitter. To be eligible to win, consumers had to include the hashtags #ForceOfFamily and #KohlsSweepstakes. That helped Kohl’s net more than 121,000 mentions, more than 52,000 more mentions than the next most-mentioned retailer. 

“While we can’t see yet whether those mentions are linking social media and sales, Kohl’s is making itself a part of the conversation,” Bransten says. “That’s very valuable.”

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