Mimecast Email Security

Yes, Microsoft 365 and on-premises Exchange are its primary deployment targets — Mimecast sits as a gateway layer in front of the mailbox, filtering mail before delivery. This layered 'in front of' approach is exactly how organizations use it alongside Microsoft's own Defender for Office 365.

They are the two most commonly compared enterprise email gateways: both offer URL rewriting, attachment sandboxing, impersonation protection, and archiving, with pricing typically negotiated per user per year. The decision usually comes down to existing vendor relationships and which console and reporting model the security team prefers.

Mimecast was taken private by private equity firm Permira in 2022, in a deal valued around $5.8 billion. The company continues operating as a standalone email security vendor under Permira ownership rather than being folded into another platform.

Its URL Protect service rewrites links in inbound emails and checks them at click time, so a URL that was safe when scanned but weaponized later still gets blocked. Attachment Protect detonates suspicious files in a sandbox before they ever reach the user's inbox.

Mimecast was founded in London in 2003 by Peter Bauer and Neil Murray, growing from a UK email continuity provider into a global email security company. It later listed on NASDAQ before the 2022 Permira take-private deal.