Exchange Online Protection (EOP)
Exchange Online Protection, or EOP, is the name of the security capability that Microsoft has built into Exchange Online and Office 365. While Microsoft is adding more advanced capabilities, it is primarily based on signature-matching technology—essentially the same approach that has been in use since the very earliest antivirus and anti-spam solutions. It provides basic defenses against the most common types of spam, viruses, and malware.
In the current environment of constantly-evolving advanced threats—with new variants appearing rapidly, designed to evade signature-matching solutions—this approach to security is still necessary, but it is far from sufficient. In order to keep your Exchange and Office 365 environments free of the latest threats, the best practice for email security is to add a more advanced solution to complement EOP.