226 lines
8.4 KiB
Nix
226 lines
8.4 KiB
Nix
# nixos-mailserver: a simple mail server
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# Copyright (C) 2016-2018 Robin Raymond
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>
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{ config, pkgs, lib, ... }:
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with (import ./common.nix { inherit config lib; });
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let
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inherit (lib.strings) concatStringsSep;
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cfg = config.mailserver;
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# valiases_postfix :: [ String ]
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valiases_postfix = lib.flatten (lib.mapAttrsToList
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(name: value:
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let to = name;
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in map (from: "${from} ${to}") (value.aliases ++ lib.singleton name))
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cfg.loginAccounts);
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# catchAllPostfix :: [ String ]
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catchAllPostfix = lib.flatten (lib.mapAttrsToList
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(name: value:
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let to = name;
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in map (from: "@${from} ${to}") value.catchAll)
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cfg.loginAccounts);
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# extra_valiases_postfix :: [ String ]
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extra_valiases_postfix =
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(map
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(from:
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let to = cfg.extraVirtualAliases.${from};
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aliasList = (l: let aliasStr = builtins.foldl' (x: y: x + y + ", ") "" l;
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in builtins.substring 0 (builtins.stringLength aliasStr - 2) aliasStr);
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in if (builtins.isList to) then "${from} " + (aliasList to)
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else "${from} ${to}")
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(builtins.attrNames cfg.extraVirtualAliases));
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# all_valiases_postfix :: [ String ]
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all_valiases_postfix = valiases_postfix ++ extra_valiases_postfix;
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# valiases_file :: Path
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valiases_file = builtins.toFile "valias"
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(lib.concatStringsSep "\n" (all_valiases_postfix ++
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catchAllPostfix));
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reject_senders_postfix = (map
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(sender:
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"${sender} REJECT")
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(cfg.rejectSender));
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reject_senders_file = builtins.toFile "reject_senders" (lib.concatStringsSep "\n" (reject_senders_postfix)) ;
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reject_recipients_postfix = (map
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(recipient:
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"${recipient} REJECT")
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(cfg.rejectRecipients));
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# rejectRecipients :: [ Path ]
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reject_recipients_file = builtins.toFile "reject_recipients" (lib.concatStringsSep "\n" (reject_recipients_postfix)) ;
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# vhosts_file :: Path
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vhosts_file = builtins.toFile "vhosts" (concatStringsSep "\n" cfg.domains);
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# vaccounts_file :: Path
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# see
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# https://blog.grimneko.de/2011/12/24/a-bunch-of-tips-for-improving-your-postfix-setup/
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# for details on how this file looks. By using the same file as valiases,
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# every alias is owned (uniquely) by its user.
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# The user's own address is already in all_valiases_postfix.
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vaccounts_file = builtins.toFile "vaccounts" (lib.concatStringsSep "\n" all_valiases_postfix);
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submissionHeaderCleanupRules = pkgs.writeText "submission_header_cleanup_rules" (''
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# Removes sensitive headers from mails handed in via the submission port.
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# See https://thomas-leister.de/mailserver-debian-stretch/
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# Uses "pcre" style regex.
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/^Received:/ IGNORE
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/^X-Originating-IP:/ IGNORE
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/^X-Mailer:/ IGNORE
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/^User-Agent:/ IGNORE
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/^X-Enigmail:/ IGNORE
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'' + lib.optionalString cfg.rewriteMessageId ''
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# Replaces the user submitted hostname with the server's FQDN to hide the
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# user's host or network.
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/^Message-ID:\s+<(.*?)@.*?>/ REPLACE Message-ID: <$1@${cfg.fqdn}>
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'');
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inetSocket = addr: port: "inet:[${toString port}@${addr}]";
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unixSocket = sock: "unix:${sock}";
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smtpdMilters =
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(lib.optional cfg.dkimSigning "unix:/run/opendkim/opendkim.sock")
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++ [ "unix:/run/rspamd/rspamd-milter.sock" ];
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policyd-spf = pkgs.writeText "policyd-spf.conf" (
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cfg.policydSPFExtraConfig
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+ (lib.optionalString cfg.debug ''
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debugLevel = 4
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''));
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mappedFile = name: "hash:/var/lib/postfix/conf/${name}";
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in
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{
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config = with cfg; lib.mkIf enable {
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services.postfix = {
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enable = true;
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hostname = "${fqdn}";
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networksStyle = "host";
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mapFiles."valias" = valiases_file;
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mapFiles."vaccounts" = vaccounts_file;
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mapFiles."reject_senders" = reject_senders_file;
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mapFiles."reject_recipients" = reject_recipients_file;
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sslCert = certificatePath;
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sslKey = keyPath;
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enableSubmission = true;
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virtual =
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(lib.concatStringsSep "\n" (all_valiases_postfix ++ catchAllPostfix));
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extraConfig =
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''
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# Extra Config
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mydestination =
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recipient_delimiter = +
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smtpd_banner = ${fqdn} ESMTP NO UCE
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disable_vrfy_command = yes
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message_size_limit = ${builtins.toString cfg.messageSizeLimit}
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# virtual mail system
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virtual_uid_maps = static:5000
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virtual_gid_maps = static:5000
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virtual_mailbox_base = ${mailDirectory}
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virtual_mailbox_domains = ${vhosts_file}
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virtual_mailbox_maps = ${mappedFile "valias"}
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virtual_transport = lmtp:unix:/run/dovecot2/dovecot-lmtp
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# sasl with dovecot
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smtpd_sasl_type = dovecot
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smtpd_sasl_path = /run/dovecot2/auth
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smtpd_sasl_auth_enable = yes
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smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
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policy-spf_time_limit = 3600s
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# reject selected senders
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smtpd_sender_restrictions = check_sender_access ${mappedFile "reject_senders"}
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# quota and spf checking
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smtpd_recipient_restrictions =
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check_recipient_access ${mappedFile "reject_recipients"},
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check_policy_service inet:localhost:12340,
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check_policy_service unix:private/policy-spf
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# TLS settings, inspired by https://github.com/jeaye/nix-files
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# Submission by mail clients is handled in submissionOptions
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smtpd_tls_security_level = may
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# strong might suffice and is computationally less expensive
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smtpd_tls_eecdh_grade = ultra
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# Disable predecessors to TLS
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smtpd_tls_protocols = !SSLv2, !SSLv3
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# Allowing AUTH on a non encrypted connection poses a security risk
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smtpd_tls_auth_only = yes
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# Log only a summary message on TLS handshake completion
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smtpd_tls_loglevel = 1
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# Disable weak ciphers as reported by https://ssl-tools.net
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# https://serverfault.com/questions/744168/how-to-disable-rc4-on-postfix
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smtpd_tls_exclude_ciphers = RC4, aNULL
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smtp_tls_exclude_ciphers = RC4, aNULL
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# Configure a non blocking source of randomness
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tls_random_source = dev:/dev/urandom
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smtpd_milters = ${lib.concatStringsSep "," smtpdMilters}
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${lib.optionalString cfg.dkimSigning "non_smtpd_milters = unix:/run/opendkim/opendkim.sock"}
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milter_protocol = 6
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milter_mail_macros = i {mail_addr} {client_addr} {client_name} {auth_type} {auth_authen} {auth_author} {mail_addr} {mail_host} {mail_mailer}
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'';
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submissionOptions =
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{
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smtpd_tls_security_level = "encrypt";
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smtpd_sasl_auth_enable = "yes";
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smtpd_sasl_type = "dovecot";
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smtpd_sasl_path = "/run/dovecot2/auth";
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smtpd_sasl_security_options = "noanonymous";
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smtpd_sasl_local_domain = "$myhostname";
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smtpd_client_restrictions = "permit_sasl_authenticated,reject";
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smtpd_sender_login_maps = "hash:/etc/postfix/vaccounts";
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smtpd_sender_restrictions = "reject_sender_login_mismatch";
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smtpd_recipient_restrictions = "reject_non_fqdn_recipient,reject_unknown_recipient_domain,permit_sasl_authenticated,reject";
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cleanup_service_name = "submission-header-cleanup";
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};
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masterConfig = {
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"policy-spf" = {
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type = "unix";
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privileged = true;
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chroot = false;
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command = "spawn";
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args = [ "user=nobody" "argv=${pkgs.pypolicyd-spf}/bin/policyd-spf" "${policyd-spf}"];
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};
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"submission-header-cleanup" = {
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type = "unix";
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private = false;
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chroot = false;
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maxproc = 0;
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command = "cleanup";
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args = ["-o" "header_checks=pcre:${submissionHeaderCleanupRules}"];
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};
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};
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};
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};
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}
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