Search engine giant strikes again!
Google just announced they will buy Postini for $625 million! Postini sells software to encrypt and archive e-mail and instant messages. Postini's security features will persuade more companies to use Mountain View, Google's e-mail service. Google hopes to further challenge Microsoft with this purchase, as Postini's security features will encourage more customers to use Gmail along with other software, spreadsheet, and instant messaging features.

The Postini acquisition is the third-biggest purchase Google has announced. The company agreed to buy DoubleClick Inc. in April for $3.1 billion and completed a $1.65 billion purchase of YouTube Inc. in November. As of 9:45 am today, Google shares rose $7.10 to $546.50. The shares had risen 17 % this year before today's trading.