Don't discount email marketing just yet. This week, Bloomberg reported that the old-school email outreach is showing new signs of vitality in a marketplace overrun with apps and social media.

The outlet reported that many big businesses--including Home Depot and Williams-Sonoma-- have recently updated their efforts to make email a lucrative outreach tool. While the story focused on what big businesses have gained from email marketing, there are certainly a few lessons for any small business owner looking to ramp up marketing in 2013.

1. Mobile email has changed the game.

Reports from Responsys Inc., a digital strategies company, show that the rising use of smartphones means that a higher number of shoppers check their emails, and do so more frequently, Bloomberg reported. In fact, 45% of shoppers now open their email through a mobile device. The big box stores get it: Major retailers have bumped up the amount of promotional emails from an average 177 emails each in 2011, to 211 in 2012. 

And according to Responsys' study, the push seems to be working. Promotional emails made $39.40 for every dollar of advertising this year, making it the most lucrative promotional tool tracked by Responsys. The second-most profitable tool, Web searches, only made $22.38 per dollar of advertising.

2. Target, target, target.

No more uniform email blasts sent across your entire mailing list. The Bloomberg report found that these large compaines sent smaller batches of emails--each specifically tuned to customers' shopping habits and interests.

And if the big guys doing it doesn't convince you, take this: Bloomberg cited a report from Experian Hitwise, an Internet traffic tracker, which found that customers are 29% more willing to open a tailored promotional email than a general one.

3. Social media marketing might not be as powerful as you thought.

While social media is often seen as the future of online marketing, studies show that it might not be the case. Bloomberg reported statistics from a recent Nielsen survey that showed that clicks on a business' Facebook page usually doesn't result in sales.

Responsys' study of promotional tools doesn’t help social media's case either. The report had social media ranked as the least profitable marketing tool, stating that it only made $12.90 for every dollar of advertising, according to Bloomberg.