Fastmail vs Mimecast

Mimecast is used by more websites in our catalog: 1,580 use Fastmail and 11,342 use Mimecast.

Mimecast sites have the higher median Ahrefs Domain Rating (Fastmail: 38, Mimecast: 51).

Between 2026-06 and 2026-07, Fastmail went from 0.22% to 0.18% of all tracked sites, while Mimecast went from 1.6% to 1.3%. Fastmail is gaining ground faster in our index.

No. A site runs a single email host, so Fastmail and Mimecast are mutually exclusive.

Adoption is counted from Site Stats Database's own crawl; Domain Rating comes from Ahrefs and traffic from DataForSEO. Figures reflect the sites we track and refresh at least monthly.