Today, Office 365 provides robust email protection against spam, viruses and malware with Exchange Online Protection (EOP).
But as hackers around the globe launch increasingly sophisticated attacks, many organizations are seeking tools that provide advanced protection.
That’s why we are pleased to introduce Exchange Online Advanced Threat Protection (ATP), a new email filtering service that provides additional protection against specific types of advanced threats. ATP is currently in private preview and is expected to be available this summer as an optional service for Office 365 commercial customers
Source : Introducing Exchange Online Advanced Threat Protection