Is Exchange vulnerable to open source? When I saw the news nugget about Yankee Group's forecast that 23% of Microsoft Exchange users may defect to open source, I had an inkling of who was behind it. Sure 'nuff, it's my dear friend Laura DiDio, who is never one to shy away from controversy. Laura's taken more than her share of bashing from the various vendors she's criticized over the years, and some people question her research methods. But I admire the way she stirs things up and gets people talking. If more Exchange users begin to examine open-source alternatives after reading this report, so much the better.  ¶ 6:52 AM