OpenSMTPD is an implementation of the SMTP protocol developed as part of the OpenBSD Project. It places particular emphasis on security, reliability and understandable configuration.
The server can receive mail for local or virtual users, relay outgoing messages and act as a conventional Internet-facing mail transfer agent. Its configuration syntax is deliberately compact and designed to make common mail-routing policies relatively easy to understand.
OpenSMTPD originated on OpenBSD, but a portable version makes it available on Linux and other Unix-like systems.
This is free and open source software.
Key Features
- Implements the server side of SMTP together with widely used protocol extensions.
- Receives and relays Internet email.
- Supports local users, virtual users and virtual domains.
- Maildir and other local delivery methods.
- TLS support for encrypted SMTP connections.
- Authentication for message submission and relaying.
- Flexible table mechanism for aliases, credentials, domains and other mappings.
- Filtering framework for applying policy to mail transactions.
- Can operate as a primary or backup mail exchanger.
- Compact, readable configuration syntax.
Website: www.opensmtpd.org
Support:
Developer: The OpenBSD Project
License: ISC License
OpenSMTPD is written in C. Learn C with our recommended free books and free tutorials.
Related Software
| Email Servers | |
|---|---|
| Exim | Highly configurable mail transfer agent |
| OpenSMTPD | Implementation of the server-side SMTP protocol with additional extensions |
| mox | Modern, secure, all-in-one email server |
| DBMail | Enables storing and retrieving mail messages from a database |
| WildDuck | Opinionated email server |
| Stalwart | All-in-one mail and collaboration server |
| Mailu | Self-hosted mail server stack |
| Mail-in-a-Box | Self-hosted email server solution |
| Postfix | Popular mail transfer agent |
| Maddy | Composable all-in-one mail server |
| Haraka | Modern SMTP server |
| Dovecot | Secure POP3 server that supports mbox and maildir mailboxes |
| Courier | Integrated mail/groupware server |
| Cyrus IMAP | Email, contacts and calendar server |
| Zimbra | Zimbra Collaboration Suite |
| Modoboa | Mail hosting and management platform |
| Citadel | Exchange-killer groupware server |
| chasquid | SMTP server with a focus on simplicity, security, and ease of operation |
| Sendmail | Mail transfer agent for sophisticated mail configurations |
| dma | DragonFly Mail Agent |
| DavMail | POP/IMAP/SMTP/Caldav/Carddav/LDAP exchange gateway |
Read our verdict in the software roundup.
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