Search by Internet on one of the address:
http://www.dobrev.com (this page is hosted in USA)
or in the computer magazines listed in the page:
If you want to receive e-mail messages when the new versions of Strawberry Prolog are released, please, type your e-mail address in the download center of our web site. You will receive two or three e-mails per year on new version releases.
If you want to stop receiving such information then you can easily unsubscribe from the same place.