Some of the online watering holes he checked were, predictably, popular with the board room set. They include the web sites of The Wall Street Journal, Bloomberg News, MarketWatch.com and The New York Times. Accounts at web sites for hotels and airlines such as United and Starwood Hotels were frequently linked to the accounts of travel heavy senior executives, as well.

"It doesn't surprise me," said Jeremiah Grossman, the Chief Technology Officer at Web security firm WhiteHat Security. "I'm an executive, and I use my corporate e-mail to sign into some of these kinds of services."

Some findings were surprising, though. Seventy six executive e-mails were linked to accounts at cloud-based storage firm Dropbox.com and 38 to accounts to the web sites nikeplus.com and garmin.com, which sell GPS-enabled athletic watches and gear.

The research does not prove, conclusively, that corporate executives use their corporate e-mail addresses to access the sites -- just that accounts linked to those email addresses exist, Cerrudo notes. Still, it's safe to assume that most are legitimate. The executives named in this story declined to comment or did not respond to requests for comment prior to publication.

Executives at technology and Internet based firms, like Hsieh at Zappos, were found to be among those who used their corporate e-mail address most freely online. Craig Newmark, the founder of the online bulletin board Craigslist.org, has accounts at DropBox, Google, Facebook, Twitter, Netflix, Plaxo, the hotel chain Starwood as well as media sites like The New York Times and Washington Post all linked to his craig@craigslist.org e-mail.