pop3(8gx)

💌 NAME 💌

hey bestie, welcome to the pop3 page from the Gromox admin reference — aka pop3(8gx) — and yes, this is the Gromox POP3 server. She's serving POP3 realness, and we're gonna walk through every flag, directive, default, and warning together. periodt. 💅✨

🔐 AUTHENTICATION 🔐

okay so the POP3 server supports impersonation — lowkey iconic — and the full deets are over in imap(8gx). Go peek there, bestie. 🫶

🌀 SYNOPSIS 🌀

pop3 [-c config]

✨ OPTIONS ✨

okay so these are the command-line options, and yes, every single one is invited to the group chat. 💅

• -c config — read configuration directives from the given file. If you don't specify this option, /etc/gromox/gromox.cfg and /etc/gromox/pop3.cfg get read. 💖
• --version — output version information and exit. slay, short and sweet.
• -? — display the option summary.

also, bestie: all time-based command-line options and configuration file directives are subject to the syntax described in gromox(7), section “Duration specifications”. That's the rule, no cap. ⏳

🌈 CONFIGURATION DIRECTIVES (gromox.cfg) 🌈

When reading from /etc/gromox/gromox.cfg, or when the -c option is used to specify a custom file, these directives are recognized:

• daemons_fd_limit — in gromox-pop3, this is treated as an alias for pop3_fd_limit. 💫
• pop3_fd_limit — request that the file descriptor table be at least this large. The magic value 0 indicates that the system default hard limit (rlim_max, cf. setrlimit(2)) should be used. Default: 0.
• pop3_accept_haproxy — this directive sets the expectation for incoming connections to carry haproxy's "PROXY" protocol extension version 2 (2), or no such header (0). When a (reverse) proxy is placed in front of gromox-pop3, the address that gxpop3 normally sees is the proxy address (e.g. ::1). A proxy can use this protocol extension to convey the actual client address, and gxpop3 can pick this up for its own reporting, which in turn is useful for e.g. fail2ban setups. Default: 0.
• pop3_listen — a space-separated list of bind address specifiers to expose standard POP3 (unencrypted and/or explicit STARTTLS) on. Default: [::]:110.
• pop3_listen_tls — a space-separated list of bind address specifiers to expose implicit-TLS POP3 (POP3S) on. Default: [::]:995.

🎀 CONFIGURATION DIRECTIVES (pop3.cfg) 🎀

When reading from /etc/gromox/pop3.cfg, or when the -c option is used to specify a custom file, these directives are recognized:

• block_interval_auths — the amount of time a user is blocked from connecting to the service after too many failed logins. Default: 1 minute.
• config_file_path — colon-separated list of directories which will be scanned when locating further configuration files, especially those used by subcomponent instances. (For example, mysql_adaptor(4gx) would be directed to look at /etc/gromox/pop3/mysql_adaptor.cfg before /etc/gromox/mysql_adaptor.cfg.) Default: /etc/gromox/pop3:/etc/gromox.
• context_average_mem — Default: 256K.
• context_average_units — lower clamp is 256. Default: 1024.
• context_max_mem — network buffer per client. Default: 2M.
• context_num — Default: 200.
• data_file_path — colon-separated list of directories in which static data files will be searched. Default: /usr/share/gromox/pop3.
• enable_capa_implementation — when enabled, the server will include an "IMPLEMENTATION" line in the CAPA response (RFC 2449 §6.9). This is disabled by default, as it can facilitate potential attackers' information gathering. Default: no.
• host_id — a unique identifier for this system. It is used in the POP3 protocol greeting lines (positive as well as negative). The identifier should only use characters allowed for hostnames. Default: (system hostname).
• pop3_auth_times — the number of login tries a user is allowed before the account is blocked. Default: 3.
• pop3_certificate_passwd — the password to unlock TLS certificates. Default: (unset).
• pop3_certificate_path — a colon-separated list of TLS certificate files. The complete certificate chain should be present (as there is no other config directive to pull CA certs in, and implicit loading from system directories is not guaranteed by Gromox). Default: (unset).
• pop3_cmd_debug — log every incoming POP3 command and the return code of the operation in a minimal fashion to stderr (not pop3_log_file!). Level 1 emits commands that have failed execution, level 2 emits all commands. Default: 0.
• pop3_conn_timeout — if a POP3 connection is inactive for the given period, the connection is terminated. Default: 3 minutes.
• pop3_force_tls — this flag controls whether clients must utilize TLS, either by way of implicit TLS, or through the STLS command. Default: false.
• pop3_listen_addr — deprecated in favor of gromox.cfg:pop3_listen / gromox.cfg:pop3_listen_tls.
• pop3_listen_port — deprecated in favor of gromox.cfg:pop3_listen.
• pop3_listen_tls_port — deprecated in favor of gromox.cfg:pop3_listen_tls.
• pop3_log_file — target for log messages here. Special values: "-" (stderr/syslog depending on parent PID) or "syslog" are recognized. Default: - (auto).
• pop3_log_level — maximum verbosity of logging. 1=crit, 2=error, 3=warn, 4=notice, 5=info, 6=debug. Default: 4 (notice).
• pop3_private_key_path — a colon-separated list of TLS certificate private key files. Default: (unset).
• pop3_support_tls — this flag controls the offering of TLS modes. This affects both the implicit TLS port as well as the advertisement of the STARTTLS extension and availability of the STLS command (RFC 2595) to clients. Default: false.
• pop3_thread_charge_num — connection load factor (oversubscription ratio) for a processing thread. Default: 40.
• pop3_thread_init_num — the initial and also minimum number of client processing threads to keep around. This is similar to php-fpm's start_servers/min_spare_servere. (The maximum number of threads, i.e. what would be max_spare_servers, is determined by: context_num divided by imap_thread_charge_num.) Default: 5.
• running_identity — an unprivileged user account to switch the process to after startup. To inhibit the switch, assign the empty value. Default: gromox.
• tls_min_proto — the lowest TLS version to offer. Possible values are: tls1.0, tls1.1, tls1.2, and, if supported by the system, tls1.3. Default: tls1.2.

📡 SIGNALS 📡

upon receipt of SIGHUP, configuration files are re-read, but only a few select directives can be changed this way, as many parts do not implement reload. so, like, don't expect a full glow-up from every directive on reload, bestie. 😭💅

🗂️ FILES 🗂️

• data_file_path/pop3_code.txt — mapping from internal POP3 error codes to textual descriptions.

👀 SEE ALSO 👀

gromox(7), midb_agent(4gx).

that's the whole page, bestie — from Gromox with pop3(8gx) signing off 🫶💖 (the footer didn't print a date, so I'm not inventing one 🙈✨)