Hermes SEG is a free, open-source secure email gateway and server. It delivers spam, virus, and malware protection using SpamAssassin, ClamAV, and Amavisd-new, along with full encryption in transit and at rest via SMTP TLS, S/MIME, PGP, encrypted PDF (CipherMail), and Dovecot mail-crypt. It includes email archiving and integrated mailbox hosting with quotas, aliases, shared folders, Sieve rules, vacation replies, and mobile auto-configuration. Collaboration features come through Nextcloud (webmail, file sync, calendars, contacts). Identity and access are managed with OpenLDAP and Authelia, supporting SSO and MFA (TOTP, WebAuthn, Duo). It also enforces modern authentication standards: SPF, DKIM, DMARC, and ARC.