Mimecast vs Microsoft Defender for Office 365
Side-by-side from the Top 11 ranking of Abnormal Security vs Proofpoint vs Mimecast: 11 Best Email Security Software 2026. Last verified July 4, 2026.
The short answer
Mimecast ranks higher on Top 11 (#3 vs #4) for IT and security leaders. Security bundled with archiving and outage continuity.
At a glance
| Mimecast | Microsoft Defender for Office 365 | |
|---|---|---|
| Top 11 rank | #3 / Abnormal Security vs Proofpoint vs Mimecast: 11 Best Email Security Software 2026 | #4 / Abnormal Security vs Proofpoint vs Mimecast: 11 Best Email Security Software 2026 |
| Score (out of 9.4) | 8.9 | 8.8 |
| Best for | Best for security plus archiving and continuity | Best native option for Microsoft 365 |
| Pricing | $$ (roughly $4 to $9 per user per month) | $ ($2/user/mo Plan 1, $5/user/mo Plan 2, or bundled in E5) |
| HQ | London, UK | Redmond, USA |
| Founded | 2003 | 2015 |
Mimecast
Security bundled with archiving and outage continuity.
www.mimecast.comSee full entry in Abnormal Security vs Proofpoint vs Mimecast: 11 Best Email Security Software 2026
Microsoft Defender for Office 365
Native M365 protection, included in E5 at $0 extra.
www.microsoft.com/en-us/security/business/siem-and-xdr/microsoft-defender-office-365See full entry in Abnormal Security vs Proofpoint vs Mimecast: 11 Best Email Security Software 2026
Methodology and scoring weights live at /methodology. No vendor pays for placement — see about.