Email is still the most common way people receive digital messages from companies, but messaging through Twitter and Facebook is more likely to cause people to press the "buy" button, according to new research.

A survey of British consumers conducted by ExactTarget, a digital marketing firm, found that 95 percent of respondents engaged with brands online in 2011. Of those people, 93 percent have given at least one company permission to send them emails, while 45 percent of consumers have "liked" a brand on Facebook and 7 percent have "followed" a business on Twitter.

But while email is used by more consumers to receive messages from companies, Twitter and Facebook are more effective at inciting a purchase, the study found -- with Twitter emerging as the big winner.

Thirty-two percent of respondents said that they were more likely to buy something from a company after "following" the company on Twitter and 24 percent of respondents said they were more likely to make a purchase after "liking" a brand on Facebook. In comparison, only 21 percent of respondents reported that a subscription to a company's e-mail list makes them more inclined to buy from that company.

To be sure, the study didn't actually track consumers' behavior online and instead relied on consumers' perceptions of which digital channels are more likely to prompt them to make a purchase. "While [consumers] may not think of email as something that makes them more likely to buy from your brand," the report noted, "[consumers] may forget to go back to your site without an email that reminds them to do so."

ExactTarget's findings come amid a recent push by Twitter and Facebook to revamp the way brands use their services to communicate with potential customers. Twitter in February unveiled a self-service system that enables small businesses to manage their marketing campaigns and budgets without having to deal with sales reps. Facebook, for its part, recently opened its new profile design, Timeline, to business, brand and organization pages, through which fans can now, among other functions, send private messages to brands.