Microsoft announced plans to close down Live Messenger in November last year but did not specify a date. The company has now begun emailing people who use the service to tell them about the changes.
According to emails sent to members, the service will close to desktop users on March 15th. Windows Live clients on other systems, such as Microsoft's Xbox games console, will continue for the time being but will eventually be closed too.
Microsoft already makes it possible for Live Messenger users to move their accounts to Skype, the internet telephony company it acquired in May last year.
Those who use Messenger can migrate their account by downloading Skype and logging in with their Live Messenger username and password. Their existing contacts will then be available within Skype.
By retiring Live Messenger, Microsoft is simply shutting down the smaller of the two services. Skype has around 280
million monthly active users - almost three times as many as Live Messenger.
Windows Live Messenger, formerly known as MSN Messenger, launched in 1999.