INSTANT MESSAGE: YOU'RE UNAUTHORISED

If you're a Microsoft MSN Messenger user, don't be surprised if you get a reply from America Online's Instant Messenger saying you're using unauthorised software.

That is the latest play in the feud which has erupted between the two online giants from the moment Microsoft launched MSN Messenger two weeks ago, according to CNET.

"As part of our blocking strategies, we are sending instant messages to MSN users which basically informs them that they are accessing AOL servers on an unauthorized client," says AOL spokeswoman Tricia Primrose. One of the more prominent features of MSN Messenger is its ability to connect to the popular AIM. AOL hit back almost at once with by blocking the upstart service from accessing its "buddy lists".

Since that salvo, CNET says, Microsoft has offered "fixes" to "punch holes" in AOL blockades, while AOL retaliates by putting up new ones.

And the feud has lured others. AOL and Apple say they'll bring forth instant message products which will allow users "seamless" communication between Mac users and AIM, CNET says, while a new AOL advisory group includes Apple founder and current interim chief executive Steve Jobs, Sun Microsystems' Bill Joy, and RealNetworks' Rob Glaser, as well as AOL's chief technology officer Marc Andressen.

Microsoft has asked AOL chief Steve Case to open the company's proprietary systems. AIM's 40 million members make it critical for rival instant message services to connect to it, and others such as Yahoo!'s Yahoo Messenger promote their ability to connect to AIM.