Microsoft will make changes to its MSN instant messaging service that will lock out users of third-party software using the service, as well as users of older versions of Microsoft's own Messenger client.
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Users have to upgrade to the latest versions of MSN or Windows Messenger by 15 October or they will no longer be able to log on, Microsoft spokesman Sean Sundwall said.
The upgrade is required because of "security issues" with the older versions of the Messenger clients.
Besides those older Messenger clients, the move also affects IM software such as Trillian, Imici and Odigo, which allow users to consolidate multiple IM accounts in one client.
"It is our expectation that those who use our service with unlicensed or unauthorised third-party clients will not be able to log on after 15 October," Sundwall said.
"We would encourage those third parties to contact us to work out agreements by which they can continue to have their customers access our network."
Though existing versions of the software may be affected, a version is said to support the latest IM protocols also found in Microsoft's MSN Messenger 6, according to postings to a forum on Trillian's website.
Microsoft sent out an e-mail alerting MSN users to upgrade. Some MSN users reported receiving a dozen or more copies of the same message. The message resembled a hoax or prank. The first line is all capital letters: "ATTENTION: IMMEDIATE ACTION REQUIRED FOR MSN AND WINDOWS MESSENGER USERS."
Users have also been told that their IM service will be cut unless they upgrade: "NOTICE: If you are not using an updated version, you will be unable to continue using your MSN Messenger or Windows Messenger Service."
In fact, the message is genuine and sent by Microsoft to all users of older Messenger clients, which third-party clients that to Microsoft's network look like older Messenger clients, Sundwall said. A relatively small number of people got multiple e-mail messages because of a snarl-up in Microsoft's e-mail system, he said.
"We sent out this e-mail because it is important that people understand that there is a new security standard in the latest Messenger clients," he said. "If you get the e-mail, that means that you have to upgrade."
Microsoft regularly sends e-mail to its customers, according to Sundwall. However, the company never sends e-mail with attachments because of the security risk. Where possible, Microsoft electronically signs the e-mail, he said.
Microsoft claims about 100 million unique users log on to the MSN Messenger service each month. Less than half of those use an old client, according to Sundwall.
Users of Messenger clients older than MSN Messenger 5.0, Windows Messenger 4.7.2000, or MSN Messenger for Mac 3.5 will be locked out, Microsoft said. To check the version number in MSN Messenger or Windows Messenger, users should select the "Help" menu in Messenger and then select "About".
Microsoft will keep reminding users that they need to upgrade. From 18 September, users who have not yet updated will receive notifications in Messenger that they need to update before 15 October.
Joris Evers writes for IDG News Service