Among 100+ other industry categories, Compete looks at US internet users’ engagement with web-based email clients.  The results of a September 2010 survey show Gmail far from being the top ranking web-based email client.

Based on unique visitors from the US IBP (internet browsing population), Gmail is much smaller in comparison to Hotmail (94% larger than Gmail) and Yahoo Mail (190% larger).

In first place comes Yahoo, holding 44% of total US internet based traffic. Next up, Hotmail with 30% of all US traffic. And in a rather distant third, Gmail ranks in.

To be fair, Gmail is the youngest web-based email client of the big three. According to Wikipedia Hotmail was established in 1994, Yahoo Mail in 1997 and Gmail in 2004.

In addition, Compete’s research has found that total webmail usage in the US is on the decline, with usage decreasing by 11% year over year from 2008 to 2010. Without knowing exactly the cause of the decline, it seems likely that the explosive use of Facebook could be one cause. For many people, Facebook has created an entirely new way of communicating with friends and family. In many respects, email may seem rather limiting in comparison to the rich features social networking can provide in keeping us connected.

This may have important implications for Facebook’s rumored email system as well as for marketers who have traditionally relied on email marketing. Facebook is rumored to be banking on the large number of connections users have to start it’s own email service, adding to the connectivity of users. It’s yet to be seen how Facebook users might engage and interact with Facebook web-based email.

Let us know your thoughts in the comments!