Glossary
EOP
Exchange Online Protection — the baseline anti-spam, anti-malware, and anti-phishing service included with Microsoft 365.
Exchange Online Protection (EOP) is the baseline email security service included with every Microsoft 365 plan that includes Exchange Online. It runs anti-spam, anti-malware, and basic anti-phishing on every incoming message, with spam confidence levels (SCL), bulk confidence levels (BCL), connection filtering, and quarantine. EOP also enforces outbound spam policies to prevent compromised users from blasting external recipients. Microsoft Defender for Office 365 adds advanced threat protection on top (Safe Links, Safe Attachments, AIR, attack simulation). EOP alone is sufficient for many small organisations; larger and security-conscious tenants typically add Defender for Office 365.