Advanced Threat Protection (ATP) similiar and complimented well with Exchange Online Protection (EOP) , is a service that helps you prevent zero-day malicious software attacks in your email environment. It does this with clever analytics, the same as webroot antivirus uses, where it puts attachements into sandboxed enviroments and tests what they do before forwarding them to you once they know it's safe

Safe Links

It also uses Safe Links technology to rewrite each external link through 365 ( acting like a web proxy ) to block any Phishing sites or websites that have been marked as unsafe due to malware or blocked file extensions. This means that even home users will get the protection they need via Webmail or via their Mobile device

Protect against unsafe attachments

All suspicious content goes through a real-time behavioral malware analysis that uses machine learning techniques to evaluate the content for suspicious activity. Unsafe attachments are sandboxed in a detonation chamber before being sent to recipients. The advantage is a malware free and cleaner inbox with better zero-day attack protection.

Reporting

A rich reporting dashboard gives you realtime stats to see what user clicked what link and where milianious links where sent from enabling you to stop future attacks and mitigate risks of existing attacks

This service comes bundled with the E5 Package in Office 365 and can be purchased as an add on for 1.50/User/Month