Bank phishing protection
A bank runs Defender for O365 Plan 2 with Safe Links + Attack Simulator training; phishing click-through dropped from 18% to 3% in six months.
Microsoft 365 (Office 365) · Productivity and Collaboration
Defender for Office 365
Advanced threat protection for M365 email and collaboration apps.
Quick answer
Microsoft Defender for Office 365 is an add-on product delivering advanced threat protection for Exchange Online and Teams/SharePoint/OneDrive. It includes Safe Links, Safe Attachments, anti-phishing AI and attack-simulation training. Two tiers: Plan 1 ($2/month) and Plan 2 ($5/month).
Defender for Office 365 layers advanced threat protection on top of M365's baseline EOP (Exchange Online Protection) anti-spam.
Safe Links re-evaluates URLs in email and Teams at click time; suspected phishing sites are blocked at the moment of click. Safe Attachments detonates file attachments in a sandbox and detects malicious behavior before delivery.
Plan 2 additionally delivers Threat Explorer, Automated Investigation and Response (AIR), Attack Simulator (phishing training) and threat hunting. Plan 2 is included inside E5.
Key features
What it offers
- Safe Links and Safe Attachments
- AI-driven anti-phishing
- Attack Simulator training
- Teams, SharePoint, OneDrive protection
- Plan 1 and Plan 2 (auto-investigation)
- Threat Explorer (Plan 2)
- Automated Investigation and Response (Plan 2)
- Mailbox intelligence — impersonation detection
Tech Summary
Important technical data
- Add-on
- Layers on top of any M365 plan
- Plan 1 price
- ~$2 per user/month
- Plan 2 price
- ~$5 per user/month
- E5 inclusion
- Plan 2 included
- Business Premium inclusion
- Defender for Business hybrid instead of Plan 1
- Console
- Microsoft Defender portal
Use CasesFinance Legal Government Education
When would you choose this product?
Law firm impersonation defense
A law firm detects BEC attacks impersonating partners through mailbox-intelligence baseline behavior.
Government training program
A government department continuously measures employee awareness via Attack Simulator; training modules auto-assign to clicked users.
University student phishing
A university blocks phishing campaigns targeting student email accounts with Defender; student awareness improves over time.
Who is it for?
Every M365 email tenant — especially financial services, legal, healthcare and other high-risk sectors.
Frequently Asked Questions
Frequently asked questions
What's the difference between EOP and Defender for O365?
EOP (Exchange Online Protection) ships baseline anti-spam, anti-malware in every M365 account. Defender for O365 — Plan 1/Plan 2 — is an add-on layering Safe Links, Safe Attachments, anti-phishing AI and AIR on top.
Run it alongside Trend Email Security?
Technically possible but rarely necessary. Two layers add cost without proportional value. Typically one layer is chosen: Defender for M365 native; Trend for multi-layer protection.
How does Attack Simulator work?
The admin selects predefined phishing templates; campaigns are sent like real phishing. Clicks and reports are tracked; clicked users auto-receive training modules.
What does Teams protection block?
Phishing links and malicious file attachments incoming through Teams chat from external users. Critical for organizations with heavy federation or guest access.
Is Plan 1 enough?
Plan 1 is a fine starting point for most organizations. SOC teams and threat-hunting workflows justify Plan 2. E5 customers already have Plan 2.
What is Mailbox Intelligence?
It learns each user's communication graph; if a new sender writes claiming to be 'the CEO' or writing style deviates from baseline, an alert is raised. Effective against impersonation attacks.
What does Threat Explorer do?
A Plan 2 feature that searches the entire tenant's email flow in real time. SOC analysts run queries like 'last 7 days, attachment-bearing email from x.com domain'.
How automated is AIR (Automated Investigation)?
In Plan 2, AIR collects forensic data for detected incidents, identifies affected users and proposes response actions. With approval (or auto-approve), it quarantines or removes content automatically.
Is an Outlook add-in required?
No client-side install required. The Report Message Outlook add-in helps users report phishing — optional but recommended.
Where is the data hosted?
In your M365 tenant's region (EU default for EU customers). Data does not leave the tenant. Aligned with GDPR.
Vendor's official product page
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