See the feature comparison for an up-to-date list of the improvements and features being carried over from Postini.
Since its launch in 2004, Gmail has invested significant resources to make its spam filtering one of the best in the industry. Customers should expect the Gmail and Postini filters to behave differently, acting more strict or lenient on different types of mail.
One of the basic principles of the Gmail spam filtering system is that it responds to input from the user about what is spam or not. Gmail does not require explicit interaction by the user to manually adjust thresholds or add approved or blocked senders. As the user marks or unmarks messages as spam, Gmail customizes filtering behavior for those types of messages.
Gmail also has comprehensive virus protection. Like Postini, Gmail utilizes two virus filtering engines for all messages, and virus protection also includes the following:
Additionally, Gmail provides increased protection against phishing-based attacks and messages containing URLs that point to malicious sites.
For more details, see How Gmail spam and virus filtering differs from Postini.
When using the Google platform with on-premise email servers, users will able to manage spam using the Quarantine Summary and the Message Center.
The Google quarantine summary is comparable to what users experience with Postini today. It's a digest that lists all messages that were marked as spam. The quarantine summary is delivered to users in their inbox and enables them to identify a message as not spam and deliver it to their on-premise inbox.
The Message Center is a web-based console that enables users to manage their spam messages. Like the Quarantine Summary, users will be able to identify a message as not spam and deliver it to their on-premise inbox.
Note: Spam messages are stored in Gmail for 30 days, while Postini typically stores messages for 14 days.