When customers receive daily-deal e-mail alerts they’ve signed up for on Delta Apparel Inc’s. e-commerce sites, including JunkFoodClothing.com, conversion rates surge, says Nathan Maxwell, Delta’s manager of e-commerce marketing. “The conversion has been tremendous—200% over the normal conversion rates for other e-mail marketing campaigns,” he says.

That’s saying a lot, because e-mail marketing in general already generates a significant portion of the retailer’s revenue, Maxwell adds.

Delta Apparel operates four e-commerce sites: Soffe.com for activewear, SaltLife.com for beachwear, JunkFoodClothing.com for casual and licensed T-shirts and related apparel, and the wholesale apparel site DeltaApparel.com, which sells to customers including screen printers, schools and individuals with no minimum order size. The company also operates a few outlet stores under the Soffe and Salt Life brands.

E-mail marketing generates from 20% to 25% of the e-commerce sales for the company’s Soffe, Salt Life and Junk Food Clothing Co. brands, Maxwell says. E-mail marketing is particularly strong at JunkFoodClothing.com, where e-commerce sales generated by e-mail rose 205% in 2011 over 2010, he adds. Junk Food Clothing specializes in selling apparel licensed by several major brands including the National Football League, Disney, Star Wars, DC Comics and The Beatles.

“E-mail is producing much bigger growth than other areas of marketing,” he says. “The standard growth through other marketing channels is maybe double digits.”

To spur even more consumer engagement with its daily deals, the retailer recently started to give customers the option of receiving daily deal alerts via SMS text messages as well as through e-mail. Although he didn’t have hard data on response rates or conversion rates tied to text messages, Maxwell says he’s encouraged by the potential of SMS to drive more sales. “What I’ve seen so far is that a high ratio of customers sign up for daily-deal text alerts,” he says. “It’s a great complement to e-mail.”

Delta Apparel manages both its e-mail marketing and text message campaigns through Bronto Software Inc. Using an administrative web page in the Bronto system, Delta can set up the same marketing campaign to run through e-mail and SMS, Maxwell says.

To learn more about holiday e-mail marketing, be sure to check out the upcoming October issue of Internet Retailer magazine.