In January this year, Google introduced DomainKeys Identified Mail (DKIM) in Google Apps - which can help reduce the risk of phishing attacks sent from spoofed domains.
And now, Google's Postini services customers can take advantage of a new capabilities dubbed Recipient Policy Framework (RPF), to help protect users on legacy email servers such as Microsoft Exchange," Google revealed.
"RPF for Postini allows customers to authenticate inbound email to help ensure that each message is actually coming from who it says it's from."
"RPF uses an open Internet standard called Sender Policy Framework to authenticate inbound emails and allows customers to define policies on how to handle emails that don't check out. When RPF is enabled by an administrator, it will help detect and block email spam and other suspicious messages," Google added.
To learn more about Postini services including email security, compliance and continuity products, please visit this web site where you can compare pricing and sign up online.
[Source: Google Enterprise blog]