Microsoft Defender for Office 365
Microsoft's email and collaboration security add-on for Microsoft 365.
Updated · AppBreakup editorial · Web
Is Microsoft Defender for Office 365 free?
No, it's a paid product
- Starting price:
- $2 per user/month (Plan 1, yearly)
- Free trial:
- 90 days (Plan 2)
Checked on Microsoft Defender for Office 365's site Nov 8, 2026
Full Microsoft Defender for Office 365 pricing and plansSwitch from Microsoft Defender for Office 365 to
All 4
MimecastPaid
ProofpointPaid
- Verified facts
- 4 of 4
- Alternatives ranked
- 4
- Approved reviews
- 0
- Visits sent from here
- 0
About Microsoft Defender for Office 365
Microsoft Defender for Office 365 adds protection on top of the basic anti-spam and anti-malware filtering that every Microsoft 365 cloud mailbox already gets. Plan 1 adds Safe Links (checks URLs when they're clicked), Safe Attachments (opens files in a sandbox), impersonation protection against business email compromise, and the same coverage for SharePoint, OneDrive and Teams. Plan 2 adds attack simulation training, Threat Explorer for investigations, and automated investigation and response that ties into Microsoft Defender XDR. It is included in some Microsoft 365 bundles, such as Business Premium and E5, and otherwise sold as a per-user add-on with annual billing. It only protects Microsoft 365 mailboxes, so it suits organisations already standardised on Microsoft; companies on Google Workspace or on-premises mail servers need a different gateway. Configuration happens in the Microsoft Defender portal, which can feel dense for small teams.
Best for: Organisations on Microsoft 365 that want stronger email security without another vendor..
Microsoft Defender for Office 365 pricing (checked Nov 8, 2026)
Each line is quoted from Microsoft Defender for Office 365's own site, with the page it came from.
| Plan or term | What it says | Checked | Source |
|---|---|---|---|
| Starting price | $2 per user/month (Plan 1, yearly) | Nov 8, 2026 | microsoft.com |
| Plan 2 price | $5 per user/month (yearly) | Nov 8, 2026 | microsoft.com |
| Free trial | 90 days (Plan 2) | Nov 8, 2026 | learn.microsoft.com |
Pros and cons
What works
- Already included in Business Premium and E5 licences
- Covers Teams, SharePoint and OneDrive, not just email
- Plan 2 links into Defender XDR for incident response
- No MX record changes since it's built into Exchange Online
Why people leave
- Only protects Microsoft 365 mailboxes
- Investigation and simulation tools need Plan 2
- Annual per-user billing for the add-on
Microsoft Defender for Office 365 vs Mimecast, Proofpoint and Barracuda Email Protection
From each app's listing and the prices verified on its own site. A dash means we haven't verified it yet.
| Attribute | Microsoft Defender for Office 365 | Mimecast | Proofpoint | Barracuda Email Protection |
|---|---|---|---|---|
| Pricing | Paid | Paid | Paid | Paid |
| Verified price | $2 per user/month (Plan 1, yearly) | — | — | — |
| Free plan | No | No | No | No |
| Open source | No | No | No | No |
| Self-hostable | No | No | No | No |
| Platforms | Web | Web | Web | Web |
Top Microsoft Defender for Office 365 alternatives
See all 4- 1Mimecast68.8
Independent secure email gateway with archiving and continuity if Microsoft's own filtering isn't enough.
- 2Proofpoint64.8
Enterprise email security leader with strong targeted-attack protection and people-centric risk reports.
- 3Barracuda Email Protection61.8
Adds AI threat detection, Microsoft 365 backup and archiving by API, and also covers Google Workspace.
- 4
SpamTitan59.4Simpler, lower-cost filtering for small businesses and MSPs, with no Microsoft licence tiers to navigate.
Why people left Microsoft Defender for Office 365
In reviewers' own words, from reviews of the apps they moved to. These are their opinions, not ours.
No switching stories yet. If you moved away from Microsoft Defender for Office 365, review the app you switched to and tell us why.
Reviews
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Microsoft Defender for Office 365: common questions
What is Microsoft Defender for Office 365?
Microsoft Defender for Office 365: Microsoft's email and collaboration security add-on for Microsoft 365. Best for organisations on Microsoft 365 that want stronger email security without another vendor. Available for Web.
Is Microsoft Defender for Office 365 free?
No, Microsoft Defender for Office 365 is a paid product. Starting price: $2 per user/month (Plan 1, yearly) (checked on Microsoft Defender for Office 365's own site).
How much does Microsoft Defender for Office 365 cost?
Microsoft Defender for Office 365 is a paid product. Starting price: $2 per user/month (Plan 1, yearly); Plan 2 price: $5 per user/month (yearly); Free trial: 90 days (Plan 2). Checked on Microsoft Defender for Office 365's own site, November 2026.
Does Microsoft Defender for Office 365 have a free trial or refund?
Free trial: 90 days (Plan 2). Source: Microsoft Defender for Office 365's own site.
Is Microsoft Defender for Office 365 open source?
No, Microsoft Defender for Office 365 is not open source.
What platforms does Microsoft Defender for Office 365 run on?
Microsoft Defender for Office 365 is available for Web.
What are the best alternatives to Microsoft Defender for Office 365?
The highest-ranked Microsoft Defender for Office 365 alternatives right now are Mimecast, Proofpoint and Barracuda Email Protection. See the full ranked list for pricing, platforms and verified facts.
Microsoft Defender for Office 365 vs Mimecast: what's the difference?
Both Microsoft Defender for Office 365 and Mimecast are paid products. Both run on Web.