{ config, pkgs, lib, ... }: with lib; let cfg = config.cloud.mail; name = "maddy"; stateDir = "/var/lib/${name}"; runtimeDir = "/run/${name}"; smtpPort = 58787; smtpsPort = 46565; imapPort = 9333; mtaStsPort = 8003; in { options.cloud.mail = { enable = mkEnableOption "Enable the email server"; package = mkOption { type = types.package; default = pkgs.maddy; }; hostname = mkOption { type = types.str; default = "mx1.nkagami.me"; description = "The hostname where the server is run on"; }; primaryDomain = mkOption { type = types.str; default = "nkagami.me"; description = "The primary email domain"; }; additionalDomains = mkOption { type = types.listOf types.str; default = [ ]; description = "Additional domain names to be used"; }; tls = { certFile = mkOption { type = types.str; description = "Path to the certificate file."; }; keyFile = mkOption { type = types.str; description = "Path to the key file."; }; }; usersFile = mkOption { type = types.path; description = '' The file containing user:hashed-password pairs to be used in the mail server. Check `maddyctl hash` to generate hashed passwords. ''; }; }; config = let configFile = pkgs.writeText "maddy.conf" '' # Globals state_dir ${stateDir} runtime_dir ${runtimeDir} # Base variables $(hostname) = ${cfg.hostname} $(primary_domain) = ${cfg.primaryDomain} $(local_domains) = ${cfg.primaryDomain} ${lib.strings.concatStringsSep " " cfg.additionalDomains} tls file "${cfg.tls.certFile}" "${cfg.tls.keyFile}" # Authentication auth.pass_table local_authdb { table file ${cfg.usersFile} } # Local storage storage.imapsql local_mailboxes { driver "postgres" dsn "dbname='${name}' user='${name}' host='/run/postgresql' sslmode=disable" appendlimit 256M } # ---------------------------------------------------------------------------- # SMTP endpoints + message routing hostname $(hostname) msgpipeline local_routing { # Insert handling for special-purpose local domains here. # e.g. # destination lists.example.org { # deliver_to lmtp tcp://127.0.0.1:8024 # } destination postmaster $(local_domains) { modify { replace_rcpt regexp "(.+)\+(.+)@(.+)" "$1@$3" replace_rcpt file /etc/maddy/aliases } deliver_to &local_mailboxes } default_destination { reject 550 5.1.1 "User doesn't exist" } } smtp tcp://0.0.0.0:25 { limits { # Up to 20 msgs/sec across max. 10 SMTP connections. all rate 20 1s all concurrency 10 } dmarc yes check { require_mx_record dkim spf } source $(local_domains) { reject 501 5.1.8 "Use Submission for outgoing SMTP" } default_source { destination postmaster $(local_domains) { deliver_to &local_routing } default_destination { reject 550 5.1.1 "User doesn't exist" } } } submission tcp://0.0.0.0:${toString smtpPort} tls://0.0.0.0:${toString smtpsPort} { limits { # Up to 50 msgs/sec across any amount of SMTP connections. all rate 50 1s } auth &local_authdb source $(local_domains) { destination postmaster $(local_domains) { deliver_to &local_routing } default_destination { modify { dkim $(primary_domain) $(local_domains) default } deliver_to &remote_queue } } default_source { reject 501 5.1.8 "Non-local sender domain" } } target.remote outbound_delivery { limits { # Up to 20 msgs/sec across max. 10 SMTP connections # for each recipient domain. destination rate 20 1s destination concurrency 10 } mx_auth { dane mtasts { cache fs fs_dir mtasts_cache/ } local_policy { min_tls_level encrypted min_mx_level none } } } target.queue remote_queue { target &outbound_delivery autogenerated_msg_domain $(primary_domain) bounce { destination postmaster $(local_domains) { deliver_to &local_routing } default_destination { reject 550 5.0.0 "Refusing to send DSNs to non-local addresses" } } } # ---------------------------------------------------------------------------- # IMAP endpoints imap tls://0.0.0.0:${toString imapPort} { auth &local_authdb storage &local_mailboxes } ''; mtaStsDir = pkgs.writeTextDir ".well-known/mta-sts.txt" '' version: STSv1 mode: enforce max_age: 604800 mx: ${cfg.hostname} ''; in mkIf cfg.enable { # users users.users."${name}" = { group = "${name}"; isSystemUser = true; }; users.groups."${name}" = { }; # database cloud.postgresql.databases = [ name ]; # MTA-STS server services.nginx.enable = true; services.nginx.virtualHosts.maddy-mta-sts = { listen = [{ addr = "127.0.0.1"; port = mtaStsPort; }]; root = mtaStsDir; }; # Firewall networking.firewall.allowedTCPPorts = [ 25 ]; # traefik cloud.traefik.hosts.maddy-smtp = { protocol = "tcp"; port = smtpPort; host = "mx1.nkagami.me"; tlsPassthrough = false; entrypoints = [ "smtp-submission" ]; }; cloud.traefik.hosts.maddy-smtps = { protocol = "tcp"; port = smtpsPort; host = "mx1.nkagami.me"; entrypoints = [ "smtp-submission-ssl" ]; }; cloud.traefik.hosts.maddy-imap = { protocol = "tcp"; port = imapPort; host = "mx1.nkagami.me"; entrypoints = [ "imap" ]; }; cloud.traefik.hosts.maddy-mta-sts = { port = mtaStsPort; host = "mta-sts.nkagami.me"; }; # maddy itself systemd.services."${name}" = { after = [ "network.target" "traefik-certs-dumper.service" ]; wantedBy = [ "multi-user.target" ]; description = "maddy mail server"; documentation = [ "man:maddy(1)" "man:maddy.conf(5)" "https://maddy.email" ]; serviceConfig = { Type = "notify"; NotifyAccess = "main"; User = name; Group = name; WorkingDirectory = "/var/lib/${name}"; ConfigurationDirectory = name; RuntimeDirectory = name; StateDirectory = name; LogsDirectory = name; ReadOnlyPaths = "/usr/lib/${name} ${cfg.tls.keyFile} ${cfg.tls.certFile}"; ReadWritePaths = "/var/lib/${name}"; # Strict sandboxing. You have no reason to trust code written by strangers from GitHub. PrivateTmp = true; ProtectHome = true; ProtectSystem = "strict"; ProtectKernelTunables = true; ProtectHostname = true; ProtectClock = true; ProtectControlGroups = true; RestrictAddressFamilies = "AF_UNIX AF_INET AF_INET6"; # Additional sandboxing. You need to disable all of these options # for privileged helper binaries (for system auth) to work correctly. NoNewPrivileges = true; PrivateDevices = true; DeviceAllow = "/dev/syslog"; RestrictSUIDSGID = true; ProtectKernelModules = true; MemoryDenyWriteExecute = true; RestrictNamespaces = true; RestrictRealtime = true; LockPersonality = true; # Graceful shutdown with a reasonable timeout. TimeoutStopSec = "7s"; KillMode = "mixed"; KillSignal = "SIGTERM"; # Required to bind on ports lower than 1024. AmbientCapabilities = "CAP_NET_BIND_SERVICE"; CapabilityBoundingSet = "CAP_NET_BIND_SERVICE"; # Bump FD limitations. Even idle mail server can have a lot of FDs open (think # of idle IMAP connections, especially ones abandoned on the other end and # slowly timing out). LimitNOFILE = 131072; # Limit processes count to something reasonable to # prevent resources exhausting due to big amounts of helper # processes launched. LimitNPROC = 512; # Restart server on any problem. Restart = "on-failure"; # ... Unless it is a configuration problem. RestartPreventExitStatus = 2; }; script = "${cfg.package}/bin/maddy -config ${configFile}"; reload = "/bin/kill -USR1 $MAINPID"; }; }; }