Hermes Secure Email Gateway vs Mimecast Secure Email Gateway

Hermes Secure Email Gateway is a self-hosted Docker Compose stack for email security, mail hosting, encryption, and collaboration. It can sit in front of Microsoft 365, Google Workspace, Exchange, or Postfix, run as a full mail server, or combine those roles in a hybrid setup. Incoming mail passes through Postfix postscreen and RBL checks, followed by scanning orchestrated by Amavisd-new with SpamAssassin and ClamAV. Hermes checks SPF, signs and verifies DKIM, enforces and aggregates DMARC, and signs and verifies ARC. Encryption options include SMTP TLS, S/MIME, PGP, encrypted PDF fallback, and Dovecot mail-crypt at rest. Full-server mode adds Dovecot mailboxes, IMAPS, POP3S, Submission, LMTP, quotas, shared mailboxes, and Sieve rules. Bundled Nextcloud supplies file sync, webmail, calendars, and contacts; Authelia provides single sign-on and multi-factor options. The free Community Edition is open source. Pro costs $750.00 per year per server and has a free 30-day trial. Hermes requires a Linux host with Docker Engine 24.0 or later and Docker Compose v2.

Mimecast Secure Email Gateway has no write-up on Specifiction yet; its figures are above.