Microsoft's SharePoint collaboration server software is, by many accounts, a huge hit, providing that seemingly irresistible formula of solid technology for free or at a low price.

Paired with Microsoft Office, SharePoint's document collaboration capabilities have proved so irresistible that Microsoft is touting SharePoint, not Exchange e-mail server, in order to lure IBM Lotus Notes users over to the Microsoft stack.

But despite Microsoft's claims to the contrary, migrations from Notes/Domino over to Outlook/Exchange/Sharepoint have been slowing for the past five years, according to analyst David Ferris of Ferris Research.

"Everyone still says that their strategic direction is to migrate to Microsoft. But as a practical matter, those who could easily do it would have already done it," Ferris said. For users still on Notes, porting to Microsoft today "would be too expensive and too disruptive."

The economic downturn and the resulting belt-tightening doesn't help, either.

Enter Silicon Valley software vendor, Mainsoft. The company was formerly a maker of development tools that allowed programmers experienced in IBM's Java EE environment to easily port their apps to Microsoft's .Net, and vice versa.

But spotting an opportunity, Mainsoft released in May its SharePoint Integrator for Lotus Notes.

"There are lots of people offering to help you migrate. Nobody before us seriously considered a co-existence strategy," said Yaacov Cohen, CEO of Mainsoft.

The software lets users of Lotus Notes versions 6.5 through 8 drag and drop Office documents to SharePoint and back. So simple, yet users such as Nader Chahine, a manager with Manhattan Home Finance, praise the Integrator.

"Without the Integrator, we may have bailed on SharePoint altogether," he said. "My team was rebelling against using SharePoint because attaching and detaching documents from SharePoint to Notes was such a nightmare."

Manhattan pays US$125 per user license for the Integrator, plus 20 percent of that annually for maintenance, said Chahine, who calls it "really reasonable."

The next version 1.5 of the Integrator is expected to be available next week. It will add the ability for users to publish their Notes e-mail and metadata to a SharePoint site, too.