In the latter parts of the study, the company looked specifically at social network membership data for users of the AOL, Gmail, Hotmail and Yahoo webmail services. Not surprisingly, the study found that Facebook was the most popular network across the board. What's more interesting is how well MySpace fared in some cases. On both the Hotmail and Yahoo webmail services, Facebook only had a small lead. Here, around 20% of all Hotmail and Yahoo webmail users were found to be on Facebook and MySpace. What does this reveal about the Hotmail and Yahoo user base? That they're a little more behind the times? Or that they've been around on the net longer and at one time had created (and possibly now abandoned) their MySpace pages? Unfortunately, the study can't provide us with these sorts of answers.

The study also showed that Twitter is far more popular among Gmail users than anyone else. In fact, on the other services, it's 4-5 times less popular than Facebook. We would like to think that's because Gmail users are just more web-savvy and cool, but it's possible that it's because they're just younger than everyone else.

Not surprisingly, LinkedIn is the least popular social network, but as Rapleaf points out, many LinkedIn users may have registered with their business email instead.

Participation Levels - Hotmail Users have Most Profiles, Gmail Users Better-Connected

When it comes to how the webmail users participate on social networks, Rapleaf found that the majority of the users have only one social media profile. But the service where the average number of profiles is the highest might surprise you - it's Hotmail. There the average is 2.5 profiles per user. Hotmail is followed by Yahoo, then AOL, and it's Gmail users who have the least number of social media profiles. That finding seems odd considering that Gmail users are younger and more likely to use Twitter in addition to Facebook. In fact, it almost seems like this data doesn't even fit with the rest of the study.

However, the discovery that Gmail users are better-connected than the other users makes more sense. On average, Gmail users have the most friends on social networks with 46.2 friends while Yahoo users have the least with 40.0.

Since again, Gmail users tend to be younger than the rest, it goes to reason that they would be in a demographic where their peers are more likely to have social membership profiles. Older webmail users, meanwhile, are still signing up for these sites. Although baby boomers and other middle-aged folks are joining sites like Facebook in droves these days, social networks are still dominated by the young.

Methodology

For the Rapleaf study, the company sampled 120,000 webmail accounts from users with @aol.com, @gmail.com, @hotmail.com and @yahoo.com email addresses. They then looked into the users' age, gender and social networking data by collecting information from public social media profiles. Obviously, in doing so, they've skewed their findings a bit, as the company notes in their original blog post. However, the sample size is large enough to form some conclusions about the members of these services, even if it relied on a particular subset of users.