In addition to massive ecommerce sales, 2013 was a record-breaking year for email marketing in the retail industry. Compared to last year, email volume increased almost 13 percent, an Experian report revealed. When inboxes are flooded with emails, they often lose their effectiveness, but the data indicated that 2013 also saw more transactions and revenue from email marketing.

According to Custora, an analytics company, email conversions have quadrupled over the last four years. Part of the reason retail marketing seems to have found a new stride in email campaigns is the strategic use of retail customer intelligence and analytics. Retailers can present consumers with personalized ads and options based on their previous purchase history, search habits and other information. These ads are more useful to customers, and more likely to catch their eye as they skim through their inbox.

Twitter recently introduced options for advertisers to use email information for target audiences. Marketing Magazine reported that Twitter now allows retailers to target users with promoted tweets based on data derived from the customers' email accounts. Companies can create lists for Twitter campaigns by securely uploading their email lists, the source said. However, part of the reason email yields more results than social media is that customers voluntarily sign up, according to Forbes, so unsolicited Twitter contact might not be as well-received.