What E5 adds over E3
Microsoft 365 E5 is E3 plus the full security and compliance stack: Defender for Identity (Entra-side threat detection), Defender for Cloud Apps (CASB), Defender for Office 365 P2 (with attack simulator), Defender for Endpoint P2 (with EDR), the full Purview suite (Insider Risk Management, Communication Compliance, Records Management, Privacy Risk), Entra ID P2 (Privileged Identity Management, Identity Protection, access reviews), Entra ID Governance entitlement management, Power BI Pro per user, and Teams Phone Standard (calling plans not included).
When E5 is the right answer
E5 pays back when you currently spend on third-party email security, third-party CASB, third-party SIEM (lower tier), third-party identity governance, or Power BI Pro standalone. Run the maths: add up your current spend on those external tools, multiply by user count, and compare to the (E5 - E3) premium. For most Australian midmarket tenants pursuing Essential Eight ML2 and consolidating tools, E5 is cheaper net of retired licences. For tenants with no current third-party tools to retire, E3 + targeted add-ons usually wins.
Common mistakes
Buying E5 then never deploying Defender for Identity, never deploying Cloud Apps, and never enabling PIM is the most common waste pattern Frontrow sees. The licence is consumed in the bill but the security uplift never lands. Run a 90-day deployment plan immediately on signing E5 — otherwise you're paying for E3 with extra steps.
Australian buying notes
Microsoft 365 E5 has frequent regional promotions in Australia, particularly around financial year and around major launches. Check with your reseller for current AU promotional pricing, and watch for the difference between Microsoft 365 E5 (the bundle) and Microsoft 365 E5 Compliance / E5 Security (the add-ons that bring E3 part-way to E5). The compliance and security add-ons sometimes make sense for non-knowledge-worker subsets.