E-mail service provider Silverpop is expected this week to announce it has added social-networking capabilities to its e-mail marketing technology.

Dubbed Share-to-Social, the feature allows marketers to place links in their messages that will allow recipients to post the messages on their Facebook or MySpace pages.

The new technology also tracks which social network the recipient posted the message on, telling marketers which one achieved the best results, according to Silverpop. The feature creates a unique tracking code for every shared message, so marketers can tell, for example, that an email posted by a recipient on Facebook was opened 1,000 times while one posted on MySpace was only opened 100 times, according to the company.

Marketers can also measure the effect of people sharing their messages with friends, according to Sillverpop. For example, if a recipient shares an e-mail on a social networking site and it gets opened 10 times, marketers using Share-to-Social can track it, the company said. They can also measure the number of opens and clicks achieved when the original email recipient’s friends post the message on their profile pages, Silverpop claimed.

“Silverpop’s new Share-to-Social feature gives marketers the ability to easily tap into the power of social networks,” said Bill Nussey, CEO of Silverpop. “It unlocks a whole new range of possibilities for viral marketing that can make a brand’s messages more effective and more targeted than ever before.”