Many schools have hesitated to adopt Google Apps for their students, citing security and privacy concerns. Gmail, as the core of Google Apps, is a tool that, by its nature, allows relatively unfettered access to anyone in the world with an email address, reports Christopher Dawson of ZDNet. Although extensive spam filtering, virus protection, and blacklisting are available through Postini, for some schools and organizations, the risk of inappropriate or dangerous use of email was a significant reason not to use Google Apps.Today, however, Google announced that it has provided Google Apps administrators with the ability to limit groups of users to internal contact only via email…