{ lib, pkgs, config, nodes, ... }:
{
  config = lib.mkIf config.myServices.mail.enable {
    services.duplyBackup.profiles.mail.excludeFile = ''
      + /var/lib/postfix
      '';
    secrets.keys = [
      {
        dest = "postfix/mysql_alias_maps";
        user = config.services.postfix.user;
        group = config.services.postfix.group;
        permissions = "0440";
        text = ''
          # We need to specify that option to trigger ssl connection
          tls_ciphers = TLSv1.2
          user = ${config.myEnv.mail.postfix.mysql.user}
          password = ${config.myEnv.mail.postfix.mysql.password}
          hosts = unix:${config.myEnv.mail.postfix.mysql.socket}
          dbname = ${config.myEnv.mail.postfix.mysql.database}
          query = SELECT DISTINCT destination
            FROM forwardings
            WHERE
              ((regex = 1 AND '%s' REGEXP CONCAT('^',source,'$') ) OR (regex = 0 AND source = '%s'))
              AND active = 1
              AND '%s' NOT IN
              (
                SELECT source
                FROM forwardings_blacklisted
                WHERE source = '%s'
              ) UNION
              SELECT 'devnull@immae.eu'
              FROM forwardings_blacklisted
              WHERE source = '%s'
          '';
      }
      {
        dest = "postfix/ldap_mailboxes";
        user = config.services.postfix.user;
        group = config.services.postfix.group;
        permissions = "0440";
        text = ''
          server_host = ldaps://${config.myEnv.mail.dovecot.ldap.host}:636
          search_base = ${config.myEnv.mail.dovecot.ldap.base}
          query_filter = ${config.myEnv.mail.dovecot.ldap.postfix_mailbox_filter}
          bind_dn = ${config.myEnv.mail.dovecot.ldap.dn}
          bind_pw = ${config.myEnv.mail.dovecot.ldap.password}
          result_attribute = immaePostfixAddress
          result_format = dummy
          version = 3
        '';
      }
      {
        dest = "postfix/mysql_sender_login_maps";
        user = config.services.postfix.user;
        group = config.services.postfix.group;
        permissions = "0440";
        text = ''
          # We need to specify that option to trigger ssl connection
          tls_ciphers = TLSv1.2
          user = ${config.myEnv.mail.postfix.mysql.user}
          password = ${config.myEnv.mail.postfix.mysql.password}
          hosts = unix:${config.myEnv.mail.postfix.mysql.socket}
          dbname = ${config.myEnv.mail.postfix.mysql.database}
          query = SELECT DISTINCT destination
            FROM forwardings
            WHERE
              (
                (regex = 1 AND CONCAT(SUBSTRING_INDEX('%u', '+', 1), '@%d') REGEXP CONCAT('^',source,'$') )
              OR
                (regex = 0 AND source = CONCAT(SUBSTRING_INDEX('%u', '+', 1), '@%d'))
              )
              AND active = 1
            UNION SELECT CONCAT(SUBSTRING_INDEX('%u', '+', 1), '@%d') AS destination
          '';
      }
      {
        dest = "postfix/mysql_sender_relays_maps";
        user = config.services.postfix.user;
        group = config.services.postfix.group;
        permissions = "0440";
        text = ''
          # We need to specify that option to trigger ssl connection
          tls_ciphers = TLSv1.2
          user = ${config.myEnv.mail.postfix.mysql.user}
          password = ${config.myEnv.mail.postfix.mysql.password}
          hosts = unix:${config.myEnv.mail.postfix.mysql.socket}
          dbname = ${config.myEnv.mail.postfix.mysql.database}
          # INSERT INTO sender_relays
          #   (`from`, owner, relay, login, password, regex, active)
          # VALUES
          #   ( 'sender@otherhost.org'
          #   , 'me@mail.immae.eu'
          #   , '[otherhost.org]:587'
          #   , 'otherhostlogin'
          #   , AES_ENCRYPT('otherhostpassword', '${config.myEnv.mail.postfix.mysql.password_encrypt}')
          #   , '0'
          #   , '1');

          query = SELECT DISTINCT `owner`
            FROM sender_relays
            WHERE
              ((regex = 1 AND '%s' REGEXP CONCAT('^',`from`,'$') ) OR (regex = 0 AND `from` = '%s'))
              AND active = 1
          '';
      }
      {
        dest = "postfix/mysql_sender_relays_hosts";
        user = config.services.postfix.user;
        group = config.services.postfix.group;
        permissions = "0440";
        text = ''
          # We need to specify that option to trigger ssl connection
          tls_ciphers = TLSv1.2
          user = ${config.myEnv.mail.postfix.mysql.user}
          password = ${config.myEnv.mail.postfix.mysql.password}
          hosts = unix:${config.myEnv.mail.postfix.mysql.socket}
          dbname = ${config.myEnv.mail.postfix.mysql.database}

          query = SELECT DISTINCT relay
            FROM sender_relays
            WHERE
              ((regex = 1 AND '%s' REGEXP CONCAT('^',`from`,'$') ) OR (regex = 0 AND `from` = '%s'))
              AND active = 1
          '';
      }
      {
        dest = "postfix/mysql_sender_relays_creds";
        user = config.services.postfix.user;
        group = config.services.postfix.group;
        permissions = "0440";
        text = ''
          # We need to specify that option to trigger ssl connection
          tls_ciphers = TLSv1.2
          user = ${config.myEnv.mail.postfix.mysql.user}
          password = ${config.myEnv.mail.postfix.mysql.password}
          hosts = unix:${config.myEnv.mail.postfix.mysql.socket}
          dbname = ${config.myEnv.mail.postfix.mysql.database}

          query = SELECT DISTINCT CONCAT(`login`, ':', AES_DECRYPT(`password`, '${config.myEnv.mail.postfix.mysql.password_encrypt}'))
            FROM sender_relays
            WHERE
              ((regex = 1 AND '%s' REGEXP CONCAT('^',`from`,'$') ) OR (regex = 0 AND `from` = '%s'))
              AND active = 1
          '';
      }
      {
        dest = "postfix/ldap_ejabberd_users_immae_fr";
        user = config.services.postfix.user;
        group = config.services.postfix.group;
        permissions = "0440";
        text = ''
          server_host = ldaps://${config.myEnv.jabber.ldap.host}:636
          search_base = ${config.myEnv.jabber.ldap.base}
          query_filter = ${config.myEnv.jabber.postfix_user_filter}
          domain = immae.fr
          bind_dn = ${config.myEnv.jabber.ldap.dn}
          bind_pw = ${config.myEnv.jabber.ldap.password}
          result_attribute = immaeXmppUid
          result_format = ejabberd@localhost
          version = 3
          '';
      }
    ] ++ (lib.mapAttrsToList (name: v: {
      dest = "postfix/scripts/${name}-env";
      user = "postfixscripts";
      group = "root";
      permissions = "0400";
      text = builtins.toJSON v.env;
    }) config.myEnv.mail.scripts);

    networking.firewall.allowedTCPPorts = [ 25 465 587 ];

    users.users.postfixscripts = {
      group = "keys";
      uid = config.ids.uids.postfixscripts;
      description = "Postfix scripts user";
    };
    users.users."${config.services.postfix.user}".extraGroups = [ "keys" ];
    services.filesWatcher.postfix = {
      restart = true;
      paths = [
        config.secrets.fullPaths."postfix/mysql_alias_maps"
        config.secrets.fullPaths."postfix/ldap_mailboxes"
        config.secrets.fullPaths."postfix/mysql_sender_login_maps"
        config.secrets.fullPaths."postfix/ldap_ejabberd_users_immae_fr"
      ];
    };
    services.postfix = {
      extraAliases = let
        toScript = name: script: pkgs.writeScript name ''
          #! ${pkgs.stdenv.shell}
          mail=$(${pkgs.coreutils}/bin/cat -)
          output=$(echo "$mail" | ${script} 2>&1)
          ret=$?

          if [ "$ret" != "0" ]; then
            echo "$mail" \
              | ${pkgs.procmail}/bin/formail -i "X-Return-Code: $ret" \
              | /run/wrappers/bin/sendmail -i scripts_error+${name}@mail.immae.eu

          messageId=$(echo "$mail" | ${pkgs.procmail}/bin/formail -x "Message-Id:")
          repeat=$(echo "$mail" | ${pkgs.procmail}/bin/formail -X "From:" -X "Received:")

          ${pkgs.coreutils}/bin/cat <<EOF | /run/wrappers/bin/sendmail -i scripts_error+${name}@mail.immae.eu
          $repeat
          To: scripts_error+${name}@mail.immae.eu
          Subject: Log from script error
          Content-Type: text/plain; charset="UTF-8"
          Content-Transfer-Encoding: 8bit
          References:$messageId
          MIME-Version: 1.0
          X-Return-Code: $ret

          Error code: $ret
          Output of message:
          --------------
          $output
          --------------
          EOF
          fi
          '';
        scripts = lib.attrsets.mapAttrs (n: v:
          toScript n (pkgs.callPackage (builtins.fetchGit { url = v.src.url; ref = "master"; rev = v.src.rev; }) { scriptEnv = "/var/secrets/postfix/scripts/${n}-env"; })
        ) config.myEnv.mail.scripts // {
          testmail = pkgs.writeScript "testmail" ''
            #! ${pkgs.stdenv.shell}
            ${pkgs.coreutils}/bin/touch \
              "/var/lib/naemon/checks/email/$(${pkgs.procmail}/bin/formail -x To: | ${pkgs.coreutils}/bin/tr -d ' <>')"
            '';
        };
      in builtins.concatStringsSep "\n" (lib.attrsets.mapAttrsToList (n: v: ''${n}: "|${v}"'') scripts);
      mapFiles = let
        recipient_maps = let
          name = n: i: "relay_${n}_${toString i}";
          pair = n: i: m: lib.attrsets.nameValuePair (name n i) (
            if m.type == "hash"
            then pkgs.writeText (name n i) m.content
            else null
          );
          pairs = n: v: lib.imap1 (i: m: pair n i m) v.recipient_maps;
        in lib.attrsets.filterAttrs (k: v: v != null) (
          lib.attrsets.listToAttrs (lib.flatten (
            lib.attrsets.mapAttrsToList pairs config.myEnv.mail.postfix.backup_domains
          ))
        );
        relay_restrictions = lib.attrsets.filterAttrs (k: v: v != null) (
          lib.attrsets.mapAttrs' (n: v:
            lib.attrsets.nameValuePair "recipient_access_${n}" (
              if lib.attrsets.hasAttr "relay_restrictions" v
              then pkgs.writeText "recipient_access_${n}" v.relay_restrictions
              else null
            )
          ) config.myEnv.mail.postfix.backup_domains
        );
        virtual_map = {
          virtual = let
            cfg = config.myEnv.monitoring.email_check.eldiron;
            address = "${cfg.mail_address}@${cfg.mail_domain}";
          in pkgs.writeText "postfix-virtual" (
            builtins.concatStringsSep "\n" (
              ["${address} testmail@localhost"] ++
              lib.attrsets.mapAttrsToList (
                n: v: lib.optionalString v.external ''
                  script_${n}@mail.immae.eu ${n}@localhost, scripts@mail.immae.eu
                ''
              ) config.myEnv.mail.scripts
            )
          );
        };
        sasl_access = {
          host_sender_login = with lib.attrsets; let
            addresses = zipAttrs (lib.flatten (mapAttrsToList
              (n: v: (map (e: { "${e}" = "${n}@immae.eu"; }) v.emails)) config.myEnv.servers));
            joined = builtins.concatStringsSep ",";
          in pkgs.writeText "host-sender-login"
            (builtins.concatStringsSep "\n" (mapAttrsToList (n: v: "${n} ${joined v}") addresses));
        };
      in
        recipient_maps // relay_restrictions // virtual_map // sasl_access;
      config = {
        ### postfix module overrides
        readme_directory = "${pkgs.postfix}/share/postfix/doc";
        smtp_tls_CAfile = lib.mkForce "";
        smtp_tls_cert_file = lib.mkForce "";
        smtp_tls_key_file = lib.mkForce "";

        message_size_limit = "1073741824"; # Don't put 0 here, it's not equivalent to "unlimited"
        mailbox_size_limit = "1073741825"; # Workaround, local delivered mails should all go through scripts
        alias_database = "\$alias_maps";

        ### Aliases scripts user
        default_privs = "postfixscripts";

        ### Virtual mailboxes config
        virtual_alias_maps = [
          "hash:/etc/postfix/virtual"
          "mysql:${config.secrets.fullPaths."postfix/mysql_alias_maps"}"
          "ldap:${config.secrets.fullPaths."postfix/ldap_ejabberd_users_immae_fr"}"
        ];
        virtual_mailbox_domains = config.myEnv.mail.postfix.additional_mailbox_domains
        ++ lib.remove null (lib.flatten (map
            (zone: map
              (e: if e.receive
              then "${e.domain}${lib.optionalString (e.domain != "") "."}${zone.name}"
              else null
              )
              (zone.withEmail or [])
            )
            config.myEnv.dns.masterZones
          ));
        virtual_mailbox_maps = [
          "ldap:${config.secrets.fullPaths."postfix/ldap_mailboxes"}"
        ];
        dovecot_destination_recipient_limit = "1";
        virtual_transport = "dovecot";

        ### Relay domains
        relay_domains = lib.flatten (lib.attrsets.mapAttrsToList (n: v: v.domains or []) config.myEnv.mail.postfix.backup_domains);
        relay_recipient_maps = lib.flatten (lib.attrsets.mapAttrsToList (n: v:
          lib.imap1 (i: m: "${m.type}:/etc/postfix/relay_${n}_${toString i}") v.recipient_maps
        ) config.myEnv.mail.postfix.backup_domains);
        smtpd_relay_restrictions = [
          "defer_unauth_destination"
        ] ++ lib.flatten (lib.attrsets.mapAttrsToList (n: v:
          if lib.attrsets.hasAttr "relay_restrictions" v
          then [ "check_recipient_access hash:/etc/postfix/recipient_access_${n}" ]
          else []
        ) config.myEnv.mail.postfix.backup_domains);

        ### Additional smtpd configuration
        smtpd_tls_received_header = "yes";
        smtpd_tls_loglevel = "1";

        ### Email sending configuration
        smtp_tls_security_level = "may";
        smtp_tls_loglevel = "1";

        ### Force ip bind for smtp
        smtp_bind_address  = config.hostEnv.ips.main.ip4;
        smtp_bind_address6 = builtins.head config.hostEnv.ips.main.ip6;

        # Use some relays when authorized senders are not myself
        smtp_sasl_mechanism_filter = "plain,login"; # GSSAPI Not correctly supported by postfix
        smtp_sasl_auth_enable = "yes";
        smtp_sasl_password_maps =
          "mysql:${config.secrets.fullPaths."postfix/mysql_sender_relays_creds"}";
        smtp_sasl_security_options = "noanonymous";
        smtp_sender_dependent_authentication = "yes";
        sender_dependent_relayhost_maps =
          "mysql:${config.secrets.fullPaths."postfix/mysql_sender_relays_hosts"}";

        ### opendkim, opendmarc, openarc milters
        non_smtpd_milters = [
          "unix:${config.myServices.mail.milters.sockets.opendkim}"
        ];
        smtpd_milters = [
          "unix:${config.myServices.mail.milters.sockets.opendkim}"
          "unix:${config.myServices.mail.milters.sockets.openarc}"
          "unix:${config.myServices.mail.milters.sockets.opendmarc}"
        ];

        smtp_use_tls = true;
        smtpd_use_tls = true;
        smtpd_tls_chain_files = builtins.concatStringsSep "," [ "/var/lib/acme/mail/full.pem" "/var/lib/acme/mail-rsa/full.pem" ];

        maximal_queue_lifetime = "6w";
        bounce_queue_lifetime = "6w";
      };
      enable = true;
      enableSmtp = true;
      enableSubmission = true;
      submissionOptions = {
        # Don’t use "long form", only commas (cf
        # http://www.postfix.org/master.5.html long form is not handled
        # well by the submission function)
        smtpd_tls_security_level = "encrypt";
        smtpd_sasl_auth_enable = "yes";
        smtpd_tls_auth_only = "yes";
        smtpd_sasl_tls_security_options = "noanonymous";
        smtpd_sasl_type = "dovecot";
        smtpd_sasl_path = "private/auth";
        smtpd_reject_unlisted_recipient = "no";
        smtpd_client_restrictions = "permit_sasl_authenticated,reject";
        smtpd_relay_restrictions = "permit_sasl_authenticated,reject";
        # Refuse to send e-mails with a From that is not handled
        smtpd_sender_restrictions =
          "reject_sender_login_mismatch,reject_unlisted_sender,permit_sasl_authenticated,reject";
        smtpd_sender_login_maps = builtins.concatStringsSep "," [
          "hash:/etc/postfix/host_sender_login"
          "mysql:${config.secrets.fullPaths."postfix/mysql_sender_relays_maps"}"
          "mysql:${config.secrets.fullPaths."postfix/mysql_sender_login_maps"}"
        ];
        smtpd_recipient_restrictions = "permit_sasl_authenticated,reject";
        milter_macro_daemon_name = "ORIGINATING";
        smtpd_milters = builtins.concatStringsSep "," [
          # FIXME: put it back when opensmtpd is upgraded and able to
          # rewrite the from header
          #"unix:/run/milter_verify_from/verify_from.sock"
          "unix:${config.myServices.mail.milters.sockets.opendkim}"
        ];
      };
      destination = ["localhost"];
      # This needs to reverse DNS
      hostname = config.hostEnv.fqdn;
      setSendmail = true;
      recipientDelimiter = "+";
      masterConfig = {
        submissions = {
          type = "inet";
          private = false;
          command = "smtpd";
          args = ["-o" "smtpd_tls_wrappermode=yes" ] ++ (let
            mkKeyVal = opt: val: [ "-o" (opt + "=" + val) ];
          in lib.concatLists (lib.mapAttrsToList mkKeyVal config.services.postfix.submissionOptions)
          );
        };
        dovecot = {
          type = "unix";
          privileged = true;
          chroot = false;
          command = "pipe";
          args = let
            # rspamd could be used as a milter, but then it cannot apply
            # its checks "per user" (milter is not yet dispatched to
            # users), so we wrap dovecot-lda inside rspamc per recipient
            # here.
            rspamc_dovecot = pkgs.writeScriptBin "rspamc_dovecot" ''
              #! ${pkgs.stdenv.shell}
              sender="$1"
              original_recipient="$2"
              user="$3"

              ${pkgs.coreutils}/bin/cat - | \
                (${pkgs.rspamd}/bin/rspamc -h ${config.myServices.mail.rspamd.sockets.worker-controller} -c bayes -d "$user" --mime || true) | \
                ${pkgs.dovecot}/libexec/dovecot/dovecot-lda -f "$sender" -a "$original_recipient" -d "$user"
              '';
          in [
            "flags=ODRhu" "user=vhost:vhost"
            "argv=${rspamc_dovecot}/bin/rspamc_dovecot \${sender} \${original_recipient} \${user}@\${nexthop}"
          ];
        };
      };
    };
    security.acme.certs."mail" = {
      postRun = ''
        systemctl restart postfix.service
        '';
      extraDomains = {
        "smtp.immae.eu" = null;
      };
    };
    security.acme.certs."mail-rsa" = {
      postRun = ''
        systemctl restart postfix.service
        '';
      extraDomains = {
        "smtp.immae.eu" = null;
      };
    };
    system.activationScripts.testmail = {
      deps = [ "users" ];
      text = let
        allCfg = config.myEnv.monitoring.email_check;
        cfg = allCfg.eldiron;
        reverseTargets = builtins.attrNames (lib.attrsets.filterAttrs (k: v: builtins.elem "eldiron" v.targets) allCfg);
        to_email = cfg': host':
          let sep = if lib.strings.hasInfix "+" cfg'.mail_address then "_" else "+";
          in "${cfg'.mail_address}${sep}${host'}@${cfg'.mail_domain}";
        mails_to_receive = builtins.concatStringsSep " " (map (to_email cfg) reverseTargets);
      in ''
        install -m 0555 -o postfixscripts -g keys -d /var/lib/naemon/checks/email
        for f in ${mails_to_receive}; do
          if [ ! -f /var/lib/naemon/checks/email/$f ]; then
            install -m 0644 -o postfixscripts -g keys /dev/null -T /var/lib/naemon/checks/email/$f
            touch -m -d @0 /var/lib/naemon/checks/email/$f
          fi
        done
        '';
    };
    systemd.services.postfix.serviceConfig.Slice = "mail.slice";
  };
}