Litmus, a company that tracks and tests email campaigns has taken a close look at where people are viewing their email. The stats, at least according to Litmus, provide some interesting insights into email habits. Outlook is still king, Webmail is in sharp decline, and Google Chrome is gaining share very rapidly.

The comparison is from July 2010 to July 2011. According to Litmus, use of mobile devices to read email is cutting into Webmail severely. Opens in mobile devices have jumped from 7% to 15% in one year. Desktop opens dropped from 55% to 53%, and Webmail dropped from 38% to 32%.

Litmus also looked at the client shares. Few will be surprised that Outlook tops the list at 37%. Hotmail comes in a distant second at 11%, followed by Yahoo Mail (10%), the iPhone (10%), Apple Mail (8%), and AOL clinging to just 1% of overall email opens. Only 2% of the clients fall under "others."I was surprised to see that Gmail accounts for only 4%.

But Gmail adoption is on the rise, according to Litmus. Yahoo Mail dropped from 44% to 31%, and Gmail rocketed from 15% to 30%. Hotmail dropped a few notches, from 39% to 33%. Reporting on Gmail use shows that Web browser shares have shifted considerably over the last year. Safari use has dropped from 25% to 8%, Chrome use was negligible last year and now accounts for 30%. Explorer has dropped from 39% to 29%, and Firefox dropped from 35% in July 2010 to 32% this July. Chrome showed smaller gains when looking at Hotmail and Yahoo Mail – but IE is the big loser across the board.

The desktop usage numbers show Outlook remains well entrenched. It has dropped 4% from July 2010 to 72% in July 2011. Apple Mail has stayed unchanged at 15%. Thunderbird is down to less than 1% this year, with only .07% of opens. Post Box, a fairly new client based on Thunderbird, is up from .006% last year to .03% this year.

The big grain of salt with this is that Litmus is only seeing opens of mail from campaigns that it's tracking. It's not seeing all kinds of regular email and it's probably not seeing the international picture particularly well. Where and how are you reading your email these days?