Lotus Notes is one of Microsoft's.
It's a frequent target at Microsoft's partner conferences and sales meetings. Want more sales, go after Notes.
The effort appears to be paying off. Microsoft says that in the last six months of 2007, more than 300 big companies, representing 2.8 million people, began switching from IBM software onto Exchange Server, Office and SharePoint Server.
The company said it expects an even greater number to switch in the next six months. That's despite the fact that the number of Notes customers has been shrinking.
"The number is getting smaller every year," said Clint Patterson, a director in Microsoft's unified communications group.
Gartner analyst Matt Cain says that among enterprises with more than 100 users, Microsoft holds about 62 percent share, compared with about 26 percent for IBM.
"Microsoft has been picking up a percentage point or two of e-mail market share based on seats for the past few years, and we expect that to continue," Cain said in an e-mail interview.
Microsoft is set to announce an updated set of tools on Monday aimed at helping even larger businesses--those with hundreds of thousands of mailboxes--move away from IBM's software and onto the Microsoft products.
That's important, Cain says, because while moving e-mail and calendar functions to Exchange is rather straightforward, "the complexity lies in migrating things like groups, archives, and contacts, and of course, Domino applications." Microsoft's tools, he said, help fill in some gaps and offer an alternative to fee-based tools from vendors such as Binary Tree and Quest.