Courier Mail Server vs Zimbra Collaboration

Courier Mail Server

Figure	Courier Mail Server	Zimbra Collaboration
Price from	Free	—
Free plan	Yes	—
Free trial	—	Yes
Open source	—	—
Web	—	Yes
Windows	—	Yes
macOS	—	Yes
Linux	Yes	Yes
iOS	—	Yes
Android	—	Yes
Self-hosted	Yes	Yes
Plans published	1	2
Spec score · Mail Server Software	8.5 (#1)	7.3 (#29)
Deployment	It can act as an intermediate mail relay, receive mail for multiple domains, or do both.	Zimbra can be deployed on-premises, in a private cloud, or in regional data centers.
Integrations	The server can use LDAP, MySQL, or PostgreSQL-based authentication databases and supports LDAP-based mail routing.	Zimbra's third-party apps page names Slack, Zoom, Dropbox, Webex, Jitsi, and Microsoft Teams.
Product	Courier is an integrated mail and groupware server providing ESMTP, IMAP, POP3, webmail, and mailing list services.	Zimbra is an enterprise email and collaboration suite with email, calendar, contacts, tasks, and file sharing.
Security	Courier supports STARTTLS and SSL for ESMTP, IMAP, POP3, and webmail; its ESMTP client can require a certificate signed by a trusted root CA.	Listed security capabilities include two-factor authentication, S/MIME email signing and encryption, SAML single sign-on, and mobile device allow/block/quarantine controls.
Support	The site lists an unmoderated courier-users mailing list for questions, bug reports, and comments, plus a separate read-only announcement list.	Standard support is business-hours only; Premier adds 24×7 support for Severity-1 issues.

Courier Mail Server has no write-up on Specifiction yet; its figures are above.

Zimbra Collaboration has no write-up on Specifiction yet; its figures are above.