We've all received e-mail promotions with a "forward this message to a friend" call-to-action, but hardly any of us ever does. According to Richard Evans, Senior Product Marketing Manager at email marketing automation firm Silverpop, "social e-mail" has the potential to be the new viral, but only if you tap into the right resources.

Richard spoke yesterday afternoon at the Lift Summit in Atlanta--a two-day conference presented by OfficeArrow and the University of Pennsylvania's Wharton Interactive Media Initiative, where real-world examples of social commerce strategies and tactics were on display--about social media integration into e-mail marketing. While Evans' message was simple--as use of social networks/media continues to gain mass adoption, integrating e-mail marketing and social media through social sharing links should be a "must include" feature in marketers' e-mail programs--it's one that's often overlooked by entrepreneurs and marketing professionals alike.

Evans and I sat down after his presentation to discuss his presentation and Silverpop's new benchmark study on social e-mail, "E-mails Gone Viral: Measuring 'Share-to-Social' Performance" in more detail. Here are three key takeaways when considering how to make your email marketing campaigns shareworthy:

The marketing landscape has shifted to one of messaging to one of engagement and sharing: An exciting new age in marketing has arrived in which interacting and building relationships with customers is the key to delivering unprecedented return on investment. Consumers are more informed than ever and are increasingly taking brands into their own hands, seeking out relationships--knowledge-based, product-based and community-based--with the companies they choose to do business with

Customers now assert more control over brands and fully expect companies to participate in dialogues with them. Powerful brands are now built by the buyers themselves through innumerable conversations--both online and off--with people they trust.

How e-mail intersects with social media: There is no doubt that social networking has become more than just an interesting phenomenon. In 2008, 33 percent of online users were monthly users of social networks and 40 percent of e-mail participants use social sites to gather product information and recommendations. That said, e-mail is still very much alive and well. Ninety-two percent of adult internet users send or read e-mail--far more than regularly visit any social network. E-mail marketing outperforms virtually all other media in terms of return on investment, and e-mail delivers one of the lowest costs per order and twice the ROI of any other digital channel.

Combining these two popular sources of information can be very powerful. Social network users are on average connected to between 150 and 200 friends, so developing an email message that is socially "shareworthy" can become viral very quickly and reach a large audience.

Tips to make e-mails more shareable: An upcoming Silverpop benchmarking study will shed light on what motivates people to share e-mail messages with their trusted social networks. The study was designed to help marketers measure their own social activity and addresses common questions such as:

• Which and how many networks should I include?
• Which networks generate the most clicks on my shared messages?

Highlights of "E-mails Gone Viral: Measuring 'Share-to-Social' Performance" include:

• While still an emerging practice, social sharing is already achieving click-through and reach rates several times that of the long used forward-to-a-friend functionality. Without offering incentives, social sharing rates average 0.5 percent while forward-to-a-friend rates are typically only a few tenths of 1 percent.
• Using conservative numbers, a Silverpop model estimated that shared e-mails evaluated for the study delivered an average increase in reach of 24.3 percent (based on original e-mails delivered), and this figure is expected to increase exponentially once sharing becomes mainstream. Further, on average, social sharing leads to an additional 1 percent of opens.
• As with e-mail in the inbox, the majority of opens and clicks of shared e-mails occurred in the first couple of days following posting on a social site. On average, the last click on a shared e-mail messages occurs about seven days after the initial share, with activity ranging from 1 to 44 days.
• While specific creative elements did not seem to factor heavily into an e-mail's shareability, it was uncovered that emails most frequently shared were more likely to feature a brand name or product in the subject line rather than a specific offer.
• Interestingly, while links to Facebook, MySpace and Twitter were included most often in e-mail messages, Bebo, Delicious and LinkedIn actually had a higher percentage of share link clicks among the networks.

For more information, read "Emails Gone Viral: Measuring 'Share-to-Social.