Users of the MSN Explorer beta may inadvertently be sending their friends seemingly personal email gushing praise over the new Microsoft program. The catch is, the spam was written by Microsoft and attached to change-of-address emails sent by some users who have signed up for MSN Explorer. Users can opt out of the message, but many have not been aware of the problem. "I recently began using a new product from Microsoft called MSN Explorer," the message begins. "With MSN Explorer, you can send and receive email, exchange instant messages with me and the millions of other people who use MSN Explorer, browse the Web and much more. MSN Explorer even offers an exciting new look for using the Web and makes it easy to find and play music online. Want to try it out? It's FREE! Just click on the link below and follow the download instructions." The letter is generated by the beta version of Microsoft Network's Explorer, according to Woody's Office Watch. MSN Explorer is Microsoft's attempt to create an integrated Internet portal that will lure new users to the MSN service. The current beta version -- called "Preview 2" by Microsoft -- includes a Web browser, email box, instant messenger and even a music player. Three innocent clicks -- or three presses of the Return key -- turn Explorer users into spammers. It works like this: during installation, the MSN Explorer setup program asks whether users would like to import their Outlook address book. Next, users who press the "return" key are asked if they would like to notify the people in their address book of a change in email. For users who select "yes", the set-up program creates an email with the line: "I am writing to let you know that I have a new email address: "(new email)". The short message is followed by the endorsement. Clicking "send" results in the email going out to every one listed in the user's Outlook address book. A Microsoft spokesperson confirmed the ads were being sent out and that users could not edit the wording. It's not automatic, by any means, but many users trying the beta have inadvertently sent the messages to others. Several users of the beta software have complained to Microsoft in a public forum, requesting that the company pull the ad-based email before the software goes gold. Recipients of the email pitchers aren't happy either. But, in one reply to an angry customer who received the email, Hotmail -- a Microsoft subsidiary -- denied that the message was spam. "The email you received was an invitation from MSN Explorer, sent on behalf of an existing user who changed their email address and wants you to try MSN Explorer," said Microsoft customer support in a letter that appeared to be an official statement. Nevertheless, even Hotmail may be ready to pull the plug on such messages in the future. "We have been in discussion with the MSN Explorer Team about these invitations," the letter continued. "And they are considering revising them so as not to confuse users." Where does advertising end and spamming begin? To have your say online click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read what others have said.