Courier Mail Server vs Mailu
Courier Mail Server
courier-mta.orgMailu
mailu.ioSide by side
| Figure | Courier Mail Server | Mailu |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | — | Yes |
| Linux | Yes | Yes |
| API | — | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 1 |
| Spec score · Mail Server Software | 8.5 (#1) | 7.9 (#18) |
| Deployment | It can act as an intermediate mail relay, receive mail for multiple domains, or do both. | Mailu runs as Docker containers and documents Docker Compose and Kubernetes deployment options. |
| Integrations | The server can use LDAP, MySQL, or PostgreSQL-based authentication databases and supports LDAP-based mail routing. | The documentation describes Nextcloud authentication through IMAP and calendar and address-book access through Radicale using WebDAV/CardDAV/CalDAV clients. |
| Limitations | Courier does not implement ETRN and is not a fully compatible replacement for sendmail or Qmail; its integrated mailbox servers do not support mbox. | The setup guide cautions that Mailu is not massively tested and recommends testing every feature before using it for a critical mail server; it also says long-term professional support seekers should consider Poste.io. |
| Product | Courier is an integrated mail and groupware server providing ESMTP, IMAP, POP3, webmail, and mailing list services. | Mailu is a free software mail server distributed as a set of Docker images. |
| 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 features include enforced TLS, DANE, MTA-STS, Let's Encrypt, outgoing DKIM, antivirus scanning, and blocking malicious attachments. |
| Support | The site lists an unmoderated courier-users mailing list for questions, bug reports, and comments, plus a separate read-only announcement list. | The project directs simple questions to its Matrix room, complex questions to GitHub discussions, and bug reports to GitHub issues; it describes itself as mostly developed in contributors' free time. |
Plans
In their own words
Courier Mail Server
Courier Mail Server has no write-up on Specifiction yet; its figures are above.