Users of the free service, which lets people upload files as big as 5MB and organize them in folders, are being greeted by a that says they have to download or delete their files by March 30. After that, the accounts will be closed and files deleted.

Yahoo is discontinuing Briefcase because users outgrew it, Yahoo said in a statement. Other services, such as Yahoo Mail and Flickr, offer far greater storage capacity, and the use of Briefcase has fallen in recent years, the company said. The move will help it to focus on services that are more widely used, according to Yahoo.

As it battles Google and Microsoft in the search arena and struggles to bring in more revenue from its array of other services, Yahoo is being driven toward tighter focus. The company announced layoffs last year and has seen its stock price plunge since a proposed acquisition by Microsoft fell apart in May 2008.

Time may have passed Briefcase by, but the idea of Internet-based file storage is alive and well. Microsoft last year announced Live Mesh, a service now in beta testing that lets users store files online, keep them synchronized across mobile devices and PCs, and access them on the road. The free DropBox application offers similar capabilities. And Google is rumored to be near introducing an online storage service called GDrive.