dovecot

dovecot [-F] [-c config_file] [-C config_dir] [-n] [-v] [-h] [-V]

-F, --foreground
    Runs the Dovecot daemon in the foreground, without detaching. Useful for debugging or containerized environments.

-c config_file, --config=config_file
    Specifies an alternative main configuration file to load instead of the default.

-C config_dir, --config-dir=config_dir
    Specifies an alternative directory containing Dovecot configuration files. All files ending with .conf in this directory are loaded.

-n, --check-config
    Checks the syntax and validity of the configuration files and exits. This does not start the server.

-v, --verbose
    Enables more verbose logging output during startup and operation, providing more detailed information for troubleshooting.

-h, --help
    Displays a brief help message explaining the command-line options and exits.

-V, --version
    Displays the Dovecot version information and exits.

Dovecot is a widely-used, free, and open-source IMAP and POP3 server designed for Unix-like operating systems. Its primary goal is to provide a highly secure, reliable, and high-performance mail delivery agent (MDA) for end-users to access their emails. Known for its ease of setup and minimal administration, Dovecot supports various mail storage formats, including Maildir, mbox, and its own optimized dbox format, which offers superior performance and crash recovery capabilities.

Key features include robust SSL/TLS support for secure communication, a flexible authentication framework supporting PAM, LDAP, SQL databases, and more. It also provides advanced features like server-side mail filtering via Sieve, efficient indexing for fast searches, and a robust architecture that minimizes the risk of security vulnerabilities. Dovecot is widely deployed by ISPs and large enterprises due to its reliability and scalability, making it a cornerstone for modern email infrastructure.

While Dovecot is designed for security, improper configuration, especially regarding authentication mechanisms, SSL/TLS certificates, or permissions on mail directories, can introduce significant security risks.
Advanced deployments, such as clustering, load balancing, or integration with complex authentication backends (e.g., Active Directory with Kerberos), can be intricate and require in-depth knowledge of both Dovecot and the integrated systems.
Performance tuning on very high-volume servers is crucial and may involve optimizing OS-level settings, mail storage, and Dovecot's internal parameters.

The dovecot binary often acts as a dispatcher for various internal utilities and subcommands that perform specific tasks. These are invoked as dovecot subcommand [args]:

• dovecot dsync: Synchronizes mailboxes between servers, commonly used for replication or migration.
• dovecot stats: Provides real-time statistics about Dovecot's performance and resource usage.
• dovecot log: Helps in querying and analyzing Dovecot's logs.
• dovecot config: Allows inspecting the parsed configuration, useful for debugging configuration issues.
• dovecot auth: A utility for testing authentication against Dovecot's authentication backends.

Dovecot was initially released in 2002, developed primarily by Timo Sirainen. It emerged as a modern alternative to existing IMAP/POP3 servers like UW-IMAP, with a strong emphasis on security, performance, and ease of administration. Its innovative features, such as the optimized dbox mail storage format and robust authentication framework, quickly made it a popular choice. Over its development history, Dovecot has continuously evolved, introducing features like director (for load balancing), replication, and comprehensive Sieve support, solidifying its position as a leading open-source mail server component.

postfix(1), sendmail(8), systemctl(1), authd(8), openssl(1)