pastila: email

flake.lock

@@ -42,11 +42,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1718208800,
-        "narHash": "sha256-US1tAChvPxT52RV8GksWZS415tTS7PV42KTc2PNDBmc=",
+        "lastModified": 1718835956,
+        "narHash": "sha256-wM9v2yIxClRYsGHut5vHICZTK7xdrUGfrLkXvSuv6s4=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "cc54fb41d13736e92229c21627ea4f22199fee6b",
+        "rev": "dd457de7e08c6d06789b1f5b88fc9327f4d96309",
         "type": "github"
       },
       "original": {
@@ -82,7 +82,6 @@
       "locked": {
         "lastModified": 1718472648,
         "narHash": "sha256-eugtFG0Z2uycs29m9XsezGoE7xBWYD7EaysDH4+RMz4=",
-        "ref": "refs/heads/pastisserie",
         "rev": "fd4b051067a09b1f76df5516514330e0d53398f7",
         "revCount": 126,
         "type": "git",

pastila/configuration.nix

@@ -17,6 +17,8 @@ in
       ./prosody.nix
       ./headscale.nix
       ./paste.nix
+      ./smtp.nix
+      ./imap.nix
     ];
 
   # Use the GRUB 2 boot loader.

pastila/imap.nix

@@ -0,0 +1,40 @@
+{ config, lib, pkgs, ... }:
+
+{
+  services.dovecot2 = {
+    enable = true;
+    enableLmtp = true;
+    sslServerCert = config.security.acme.certs."imap".directory + "/cert.pem";
+    sslServerKey = config.security.acme.certs."imap".directory + "/key.pem";
+
+    mailLocation = "/var/vmail/%d/%n/Maildir";
+    extraConfig = ''
+    # Exim auth
+    service auth {
+      unix_listener auth-client {
+        mode = 0600
+	user = ${config.services.exim.user}
+      }
+    }
+    
+    passdb {
+      driver = passwd-file
+      args = username_format=%n /etc/secrets/dovecot/passwd
+    }
+
+    userdb {
+      driver = static
+      args = uid=vmail gid=vmail home=/var/vmail/%d/%n
+    }
+    '';
+  };
+
+  security.acme.certs."imap" = {
+    domain = "imap.isomorphis.me";
+    extraDomainNames = [
+      "imap.tremeg.net"
+      "imap.gueneau.me"
+    ];
+    # group = config.services.dovecot2.group;
+  };
+}

pastila/smtp.nix

@@ -0,0 +1,949 @@
+{ config, lib, pkgs, ... }:
+
+let
+  opendkim_selector = "21062024";
+  exim = pkgs.exim.override {
+    enableAuthDovecot = true;
+  };
+in
+{
+  services.opendkim = {
+    enable = true;
+    selector = opendkim_selector;
+    domains = "csl:isomorphis.me,tremeg.net,gueneau.me";
+  };
+
+  users.groups."vmail" = {};
+  users.users."vmail" = {
+    isSystemUser = true;
+    group = "vmail";
+    home = "/var/vmail";
+  };
+
+  users.users."exim".extraGroups = [
+    config.services.opendkim.group
+  ];
+
+  services.exim = {
+    enable = true;
+    package = exim;
+    config = ''
+######################################################################
+#                    MAIN CONFIGURATION SETTINGS                     #
+######################################################################
+
+# Specify your host's canonical name here. This should normally be the fully
+# qualified "official" name of your host. If this option is not set, the
+# uname() function is called to obtain the name. In many cases this does
+# the right thing and you need not set anything explicitly.
+
+primary_hostname = pastila.isomorphis.me
+
+# The next three settings create two lists of domains and one list of hosts.
+# These lists are referred to later in this configuration using the syntax
+# +local_domains, +relay_to_domains, and +relay_from_hosts, respectively. They
+# are all colon-separated lists:
+
+domainlist local_domains = @ : isomorphis.me : tremeg.net : gueneau.me : armael.net
+domainlist relay_to_domains = polyno.me
+hostlist   relay_from_hosts = 127.0.0.1
+hostlist   host_auth_accept_relay = *
+
+# Most straightforward access control requirements can be obtained by
+# appropriate settings of the above options. In more complicated situations,
+# you may need to modify the Access Control Lists (ACLs) which appear later in
+# this file.
+
+# The first setting specifies your local domains, for example:
+#
+#   domainlist local_domains = my.first.domain : my.second.domain
+#
+# You can use "@" to mean "the name of the local host", as in the default
+# setting above. This is the name that is specified by primary_hostname,
+# as specified above (or defaulted). If you do not want to do any local
+# deliveries, remove the "@" from the setting above. If you want to accept mail
+# addressed to your host's literal IP address, for example, mail addressed to
+# "user@[192.168.23.44]", you can add "@[]" as an item in the local domains
+# list. You also need to uncomment "allow_domain_literals" below. This is not
+# recommended for today's Internet.
+
+# The second setting specifies domains for which your host is an incoming relay.
+# If you are not doing any relaying, you should leave the list empty. However,
+# if your host is an MX backup or gateway of some kind for some domains, you
+# must set relay_to_domains to match those domains. For example:
+#
+# domainlist relay_to_domains = *.myco.com : my.friend.org
+#
+# This will allow any host to relay through your host to those domains.
+# See the section of the manual entitled "Control of relaying" for more
+# information.
+
+
+# The third setting specifies hosts that can use your host as an outgoing relay
+# to any other host on the Internet. Such a setting commonly refers to a
+# complete local network as well as the localhost. For example:
+#
+# hostlist relay_from_hosts = 127.0.0.1 : 192.168.0.0/16
+#
+# The "/16" is a bit mask (CIDR notation), not a number of hosts. Note that you
+# have to include 127.0.0.1 if you want to allow processes on your host to send
+# SMTP mail by using the loopback address. A number of MUAs use this method of
+# sending mail.
+
+# All three of these lists may contain many different kinds of item, including
+# wildcarded names, regular expressions, and file lookups. See the reference
+# manual for details. The lists above are used in the access control lists for
+# checking incoming messages. The names of these ACLs are defined here:
+
+acl_smtp_rcpt = acl_check_rcpt
+acl_smtp_data = acl_check_spam
+
+# You should not change those settings until you understand how ACLs work.
+
+
+# If you are running a version of Exim that was compiled with the content-
+# scanning extension, you can cause incoming messages to be automatically
+# scanned for viruses. You have to modify the configuration in two places to
+# set this up. The first of them is here, where you define the interface to
+# your scanner. This example is typical for ClamAV; see the manual for details
+# of what to set for other virus scanners. The second modification is in the
+# acl_check_data access control list (see below).
+
+# av_scanner = clamd:/tmp/clamd
+
+
+# For spam scanning, there is a similar option that defines the interface to
+# SpamAssassin. You do not need to set this if you are using the default, which
+# is shown in this commented example. As for virus scanning, you must also
+# modify the acl_check_data access control list to enable spam scanning.
+
+# spamd_address = 127.0.0.1 11333 variant=rspamd
+
+
+# If Exim is compiled with support for TLS, you may want to enable the
+# following options so that Exim allows clients to make encrypted
+# connections. In the authenticators section below, there are template
+# configurations for plaintext username/password authentication. This kind
+# of authentication is only safe when used within a TLS connection, so the
+# authenticators will only work if the following TLS settings are turned on
+# as well.
+
+# Allow any client to use TLS.
+
+tls_advertise_hosts = *
+
+# Specify the location of the Exim server's TLS certificate and private key.
+# The private key must not be encrypted (password protected). You can put
+# the certificate and private key in the same file, in which case you only
+# need the first setting, or in separate files, in which case you need both
+# options.
+
+tls_certificate = ${config.security.acme.certs."smtp".directory + "/cert.pem"}
+tls_privatekey = ${config.security.acme.certs."smtp".directory + "/key.pem"}
+
+# (use the defaults as those are most likely outdated)
+# openssl_options = +no_sslv2 +no_sslv3
+# tls_require_ciphers = HIGH:!DES:!RC4:!MD5
+
+
+# In order to support roaming users who wish to send email from anywhere,
+# you may want to make Exim listen on other ports as well as port 25, in
+# case these users need to send email from a network that blocks port 25.
+# The standard port for this purpose is port 587, the "message submission"
+# port. See RFC 4409 for details. Microsoft MUAs cannot be configured to
+# talk the message submission protocol correctly, so if you need to support
+# them you should also allow TLS-on-connect on the traditional but
+# non-standard port 465.
+
+daemon_smtp_ports = 25 : 465 : 587
+tls_on_connect_ports = 465
+
+# Specify the domain you want to be added to all unqualified addresses
+# here. An unqualified address is one that does not contain an "@" character
+# followed by a domain. For example, "caesar@rome.example" is a fully qualified
+# address, but the string "caesar" (i.e. just a login name) is an unqualified
+# email address. Unqualified addresses are accepted only from local callers by
+# default. See the recipient_unqualified_hosts option if you want to permit
+# unqualified addresses from remote sources. If this option is not set, the
+# primary_hostname value is used for qualification.
+
+qualify_domain = isomorphis.me
+
+
+# If you want unqualified recipient addresses to be qualified with a different
+# domain to unqualified sender addresses, specify the recipient domain here.
+# If this option is not set, the qualify_domain value is used.
+
+# qualify_recipient =
+
+
+# The following line must be uncommented if you want Exim to recognize
+# addresses of the form "user@[10.11.12.13]" that is, with a "domain literal"
+# (an IP address) instead of a named domain. The RFCs still require this form,
+# but it makes little sense to permit mail to be sent to specific hosts by
+# their IP address in the modern Internet. This ancient format has been used
+# by those seeking to abuse hosts by using them for unwanted relaying. If you
+# really do want to support domain literals, uncomment the following line, and
+# see also the "domain_literal" router below.
+
+# allow_domain_literals
+
+
+# No deliveries will ever be run under the uids of users specified by
+# never_users (a colon-separated list). An attempt to do so causes a panic
+# error to be logged, and the delivery to be deferred. This is a paranoic
+# safety catch. There is an even stronger safety catch in the form of the
+# FIXED_NEVER_USERS setting in the configuration for building Exim. The list of
+# users that it specifies is built into the binary, and cannot be changed. The
+# option below just adds additional users to the list. The default for
+# FIXED_NEVER_USERS is "root", but just to be absolutely sure, the default here
+# is also "root".
+
+# Note that the default setting means you cannot deliver mail addressed to root
+# as if it were a normal user. This isn't usually a problem, as most sites have
+# an alias for root that redirects such mail to a human administrator.
+
+never_users = root
+
+
+# The setting below causes Exim to do a reverse DNS lookup on all incoming
+# IP calls, in order to get the true host name. If you feel this is too
+# expensive, you can specify the networks for which a lookup is done, or
+# remove the setting entirely.
+
+host_lookup = *
+
+
+# The settings below, which are actually the same as the defaults in the
+# code, cause Exim to make RFC 1413 (ident) callbacks for all incoming SMTP
+# calls. You can limit the hosts to which these calls are made, and/or change
+# the timeout that is used. If you set the timeout to zero, all RFC 1413 calls
+# are disabled. RFC 1413 calls are cheap and can provide useful information
+# for tracing problem messages, but some hosts and firewalls have problems
+# with them. This can result in a timeout instead of an immediate refused
+# connection, leading to delays on starting up SMTP sessions. (The default was
+# reduced from 30s to 5s for release 4.61.)
+
+rfc1413_hosts = *
+rfc1413_query_timeout = 5s
+
+
+# By default, Exim expects all envelope addresses to be fully qualified, that
+# is, they must contain both a local part and a domain. If you want to accept
+# unqualified addresses (just a local part) from certain hosts, you can specify
+# these hosts by setting one or both of
+#
+# sender_unqualified_hosts =
+# recipient_unqualified_hosts =
+#
+# to control sender and recipient addresses, respectively. When this is done,
+# unqualified addresses are qualified using the settings of qualify_domain
+# and/or qualify_recipient (see above).
+
+
+# If you want Exim to support the "percent hack" for certain domains,
+# uncomment the following line and provide a list of domains. The "percent
+# hack" is the feature by which mail addressed to x%y@z (where z is one of
+# the domains listed) is locally rerouted to x@y and sent on. If z is not one
+# of the "percent hack" domains, x%y is treated as an ordinary local part. This
+# hack is rarely needed nowadays; you should not enable it unless you are sure
+# that you really need it.
+#
+# percent_hack_domains =
+#
+# As well as setting this option you will also need to remove the test
+# for local parts containing % in the ACL definition below.
+
+
+# When Exim can neither deliver a message nor return it to sender, it "freezes"
+# the delivery error message (aka "bounce message"). There are also other
+# circumstances in which messages get frozen. They will stay on the queue for
+# ever unless one of the following options is set.
+
+# This option unfreezes frozen bounce messages after two days, tries
+# once more to deliver them, and ignores any delivery failures.
+
+ignore_bounce_errors_after = 2d
+
+# This option cancels (removes) frozen messages that are older than a week.
+
+timeout_frozen_after = 7d
+
+
+# By default, messages that are waiting on Exim's queue are all held in a
+# single directory called "input" which it itself within Exim's spool
+# directory. (The default spool directory is specified when Exim is built, and
+# is often /var/spool/exim/.) Exim works best when its queue is kept short, but
+# there are circumstances where this is not always possible. If you uncomment
+# the setting below, messages on the queue are held in 62 subdirectories of
+# "input" instead of all in the same directory. The subdirectories are called
+# 0, 1, ... A, B, ... a, b, ... z. This has two benefits: (1) If your file
+# system degrades with many files in one directory, this is less likely to
+# happen; (2) Exim can process the queue one subdirectory at a time instead of
+# all at once, which can give better performance with large queues.
+
+# split_spool_directory = true
+
+
+# If you're in a part of the world where ASCII is not sufficient for most
+# text, then you're probably familiar with RFC2047 message header extensions.
+# By default, Exim adheres to the specification, including a limit of 76
+# characters to a line, with encoded words fitting within a line.
+# If you wish to use decoded headers in message filters in such a way
+# that successful decoding of malformed messages matters, you may wish to
+# configure Exim to be more lenient.
+#
+# check_rfc2047_length = false
+#
+# In particular, the Exim maintainers have had multiple reports of problems
+# from Russian administrators of issues until they disable this check,
+# because of some popular, yet buggy, mail composition software.
+
+
+# If you wish to be strictly RFC compliant, or if you know you'll be
+# exchanging email with systems that are not 8-bit clean, then you may
+# wish to disable advertising 8BITMIME.  Uncomment this option to do so.
+
+# accept_8bitmime = false
+
+######################################################################
+#                       ACL CONFIGURATION                            #
+#         Specifies access control lists for incoming SMTP mail      #
+######################################################################
+
+begin acl
+
+# .include /etc/mail/acl-greylist-sqlite
+
+# This access control list is used for every RCPT command in an incoming
+# SMTP message. The tests are run in order until the address is either
+# accepted or denied.
+
+acl_check_rcpt:
+
+  # Accept if the source is local SMTP (i.e. not over TCP/IP). We do this by
+  # testing for an empty sending host field.
+
+  accept  hosts = :
+          control = dkim_disable_verify
+
+  #############################################################################
+  # The following section of the ACL is concerned with local parts that contain
+  # @ or % or ! or / or | or dots in unusual places.
+  #
+  # The characters other than dots are rarely found in genuine local parts, but
+  # are often tried by people looking to circumvent relaying restrictions.
+  # Therefore, although they are valid in local parts, these rules lock them
+  # out, as a precaution.
+  #
+  # Empty components (two dots in a row) are not valid in RFC 2822, but Exim
+  # allows them because they have been encountered. (Consider local parts
+  # constructed as "firstinitial.secondinitial.familyname" when applied to
+  # someone like me, who has no second initial.) However, a local part starting
+  # with a dot or containing /../ can cause trouble if it is used as part of a
+  # file name (e.g. for a mailing list). This is also true for local parts that
+  # contain slashes. A pipe symbol can also be troublesome if the local part is
+  # incorporated unthinkingly into a shell command line.
+  #
+  # Two different rules are used. The first one is stricter, and is applied to
+  # messages that are addressed to one of the local domains handled by this
+  # host. The line "domains = +local_domains" restricts it to domains that are
+  # defined by the "domainlist local_domains" setting above. The rule  blocks
+  # local parts that begin with a dot or contain @ % ! / or |. If you have
+  # local accounts that include these characters, you will have to modify this
+  # rule.
+
+  deny    message       = Restricted characters in address
+          domains       = +local_domains
+          local_parts   = ^[.] : ^.*[@%!/|]
+
+  # The second rule applies to all other domains, and is less strict. The line
+  # "domains = !+local_domains" restricts it to domains that are NOT defined by
+  # the "domainlist local_domains" setting above. The exclamation mark is a
+  # negating operator. This rule allows your own users to send outgoing
+  # messages to sites that use slashes and vertical bars in their local parts.
+  # It blocks local parts that begin with a dot, slash, or vertical bar, but
+  # allows these characters within the local part. However, the sequence /../
+  # is barred. The use of @ % and ! is blocked, as before. The motivation here
+  # is to prevent your users (or your users' viruses) from mounting certain
+  # kinds of attack on remote sites.
+
+  deny    message       = Restricted characters in address
+          domains       = !+local_domains
+          local_parts   = ^[./|] : ^.*[@%!] : ^.*/\\.\\./
+  #############################################################################
+
+  # Accept mail to postmaster in any local domain, regardless of the source,
+  # and without verifying the sender.
+
+  accept  local_parts   = postmaster
+          domains       = +local_domains
+
+  # Deny unless the sender address can be verified.
+
+  require verify        = sender
+
+  # Accept if the message comes from one of the hosts for which we are an
+  # outgoing relay. It is assumed that such hosts are most likely to be MUAs,
+  # so we set control=submission to make Exim treat the message as a
+  # submission. It will fix up various errors in the message, for example, the
+  # lack of a Date: header line. If you are actually relaying out out from
+  # MTAs, you may want to disable this. If you are handling both relaying from
+  # MTAs and submissions from MUAs you should probably split them into two
+  # lists, and handle them differently.
+
+  # Recipient verification is omitted here, because in many cases the clients
+  # are dumb MUAs that don't cope well with SMTP error responses. If you are
+  # actually relaying out from MTAs, you should probably add recipient
+  # verification here.
+
+  # Note that, by putting this test before any DNS black list checks, you will
+  # always accept from these hosts, even if they end up on a black list. The
+  # assumption is that they are your friends, and if they get onto a black
+  # list, it is a mistake.
+
+  accept  hosts         = +relay_from_hosts
+          control       = submission
+          control       = dkim_disable_verify
+
+  # Accept if the message arrived over an authenticated connection, from
+  # any host. Again, these messages are usually from MUAs, so recipient
+  # verification is omitted, and submission mode is set. And again, we do this
+  # check before any black list tests.
+
+  accept  authenticated = *
+          control       = submission/sender_retain
+          control       = dkim_disable_verify
+
+  # Insist that any other recipient address that we accept is either in one of
+  # our local domains, or is in a domain for which we explicitly allow
+  # relaying. Any other domain is rejected as being unacceptable for relaying.
+
+  require message = relay not permitted
+          domains = +local_domains : +relay_to_domains
+
+  # We also require all accepted addresses to be verifiable. This check will
+  # do local part verification for local domains, but only check the domain
+  # for remote domains. The only way to check local parts for the remote
+  # relay domains is to use a callout (add /callout), but please read the
+  # documentation about callouts before doing this.
+
+  require verify = recipient
+
+  #############################################################################
+  # There are no default checks on DNS black lists because the domains that
+  # contain these lists are changing all the time. However, here are two
+  # examples of how you can get Exim to perform a DNS black list lookup at this
+  # point. The first one denies, whereas the second just warns.
+  #
+  # deny    message       = rejected because $sender_host_address is in a black list at $dnslist_domain\n$dnslist_text
+  #         dnslists      = black.list.example
+  #
+  # warn    dnslists      = black.list.example
+  #         add_header    = X-Warning: $sender_host_address is in a black list at $dnslist_domain
+  #         log_message   = found in $dnslist_domain
+  #############################################################################
+
+  #############################################################################
+  # This check is commented out because it is recognized that not every
+  # sysadmin will want to do it. If you enable it, the check performs
+  # Client SMTP Authorization (csa) checks on the sending host. These checks
+  # do DNS lookups for SRV records. The CSA proposal is currently (May 2005)
+  # an Internet draft. You can, of course, add additional conditions to this
+  # ACL statement to restrict the CSA checks to certain hosts only.
+  #
+  # require verify = csa
+  #############################################################################
+
+  # At this point, the address has passed all the checks that have been
+  # configured, so we accept it unconditionally.
+
+  accept
+
+# This ACL is used after the contents of a message have been received. This
+# is the ACL in which you can test a message's headers or body, and in
+# particular, this is where you can invoke external virus or spam scanners.
+# Some suggested ways of configuring these tests are shown below, commented
+# out. Without any tests, this ACL accepts all messages. If you want to use
+# such tests, you must ensure that Exim is compiled with the content-scanning
+# extension (WITH_CONTENT_SCAN=yes in Local/Makefile).
+
+acl_check_data:
+
+  # warn  message = X-MIME-Error: $demime_reason
+  #       demime = *
+  #       condition = ''${if >{$demime_errorlevel}{0}{1}{0}}
+  #       set acl_m_greylistreasons = Message has MIME error: $demime_reason\n$acl_m_greylistreasons
+
+  # warn  condition = ''${if and {                                  \
+  #                       {match {''${lc:$h_subject:}}{^re:}}       \
+  #                       {!def:h_References:}                    \
+  #                       {!def:h_In-Reply-To:}                   \
+  #                    } {1}{0}}
+  #       message = X-Bad-Reply: 'Re:' in Subject but no References or In-Reply-To headers
+  #       set acl_m_greylistreasons = Message has 'Re:' in Subject: but neither References: nor In-Reply-To:\n$acl_m_greylistreasons
+
+  # warn condition = ''${if !def:h_Message-ID: {1}}
+  #       set acl_m_greylistreasons = Message has no Message-Id: header\n$acl_m_greylistreasons
+
+  # warn dnslists = psbl.surriel.org
+  #      set acl_m_greylistreasons = Host listed in $dnslist_domain blacklist: $dnslist_text\n$acl_m_greylistreasons
+
+  # require acl = greylist_mail
+
+  # Deny if the message contains a virus. Before enabling this check, you
+  # must install a virus scanner and set the av_scanner option above.
+  #
+  # deny    malware    = *
+  #         message    = This message contains a virus ($malware_name).
+
+  # Add headers to a message if it is judged to be spam. Before enabling this,
+  # you must install SpamAssassin. You may also need to set the spamd_address
+  # option above.
+  #
+  # warn    spam       = nobody
+  #         add_header = X-Spam_score: $spam_score\n\
+  #                      X-Spam_score_int: $spam_score_int\n\
+  #                      X-Spam_bar: $spam_bar\n\
+  #                      X-Spam_report: $spam_report
+
+  # Accept the message.
+
+  accept
+
+acl_check_spam:
+  # do not scan messages submitted from our own hosts
+  # +relay_from_hosts is assumed to be a list of hosts in configuration
+  accept hosts = +relay_from_hosts
+
+  # do not scan messages from submission port (or maybe you want to?)
+  accept condition = ''${if eq{$interface_port}{587}}
+
+  # skip scanning for authenticated users (if desired?)
+  accept authenticated = *
+
+  # add spam-score and spam-report header when told by rspamd
+  warn  spam       = nobody:true
+        condition  = ''${if eq{$spam_action}{add header}}
+        add_header = X-Spam-Score: $spam_score ($spam_bar)
+        add_header = X-Spam-Report: $spam_report
+
+  # $spam_action is the action recommended by rspamd
+  # $spam_score is the message score (we unlikely need it)
+  # $spam_score_int is spam score multiplied by 10
+  # $spam_report lists symbols matched & protocol messages
+  # $spam_bar is a visual indicator of spam/ham level
+
+  # use greylisting available in rspamd v1.3+
+  defer message    = Please try again later
+        condition  = ''${if eq{$spam_action}{soft reject}}
+
+  deny  message    = Message discarded as high-probability spam
+        condition  = ''${if eq{$spam_action}{reject}}
+
+  accept
+
+######################################################################
+#                      ROUTERS CONFIGURATION                         #
+#               Specifies how addresses are handled                  #
+######################################################################
+#     THE ORDER IN WHICH THE ROUTERS ARE DEFINED IS IMPORTANT!       #
+# An address is passed to each router in turn until it is accepted.  #
+######################################################################
+
+begin routers
+
+# This router routes to remote hosts over SMTP by explicit IP address,
+# when an email address is given in "domain literal" form, for example,
+# <user@[192.168.35.64]>. The RFCs require this facility. However, it is
+# little-known these days, and has been exploited by evil people seeking
+# to abuse SMTP relays. Consequently it is commented out in the default
+# configuration. If you uncomment this router, you also need to uncomment
+# allow_domain_literals above, so that Exim can recognize the syntax of
+# domain literal addresses.
+
+# domain_literal:
+#   driver = ipliteral
+#   domains = ! +local_domains
+#   transport = remote_smtp
+
+
+# This router routes addresses that are not in local domains by doing a DNS
+# lookup on the domain name. The exclamation mark that appears in "domains = !
+# +local_domains" is a negating operator, that is, it can be read as "not". The
+# recipient's domain must not be one of those defined by "domainlist
+# local_domains" above for this router to be used.
+#
+# If the router is used, any domain that resolves to 0.0.0.0 or to a loopback
+# interface address (127.0.0.0/8) is treated as if it had no DNS entry. Note
+# that 0.0.0.0 is the same as 0.0.0.0/32, which is commonly treated as the
+# local host inside the network stack. It is not 0.0.0.0/0, the default route.
+# If the DNS lookup fails, no further routers are tried because of the no_more
+# setting, and consequently the address is unrouteable.
+
+dnslookup:
+  driver = dnslookup
+  domains = ! +local_domains
+  transport = remote_smtp
+  ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
+  no_more
+
+
+# The remaining routers handle addresses in the local domain(s), that is those
+# domains that are defined by "domainlist local_domains" above.
+
+
+# This router handles aliasing using a linearly searched alias file with the
+# name /etc/mail/aliases. When this configuration is installed automatically,
+# the name gets inserted into this file from whatever is set in Exim's
+# build-time configuration. The default path is the traditional /etc/mail/aliases.
+# If you install this configuration by hand, you need to specify the correct
+# path in the "data" setting below.
+#
+##### NB  You must ensure that the alias file exists. It used to be the case
+##### NB  that every Unix had that file, because it was the Sendmail default.
+##### NB  These days, there are systems that don't have it. Your aliases
+##### NB  file should at least contain an alias for "postmaster".
+#
+# If any of your aliases expand to pipes or files, you will need to set
+# up a user and a group for these deliveries to run under. You can do
+# this by uncommenting the "user" option below (changing the user name
+# as appropriate) and adding a "group" option if necessary. Alternatively, you
+# can specify "user" on the transports that are used. Note that the transports
+# listed below are the same as are used for .forward files; you might want
+# to set up different ones for pipe and file deliveries from aliases.
+
+system_aliases:
+  driver = redirect
+  allow_fail
+  allow_defer
+  data = ''${lookup{$local_part}lsearch{/etc/secrets/exim/aliases}}
+# user = exim
+  file_transport = address_file
+  pipe_transport = address_pipe
+
+# This router handles forwarding using traditional .forward files in users'
+# home directories. If you want it also to allow mail filtering when a forward
+# file starts with the string "# Exim filter" or "# Sieve filter", uncomment
+# the "allow_filter" option.
+
+# The no_verify setting means that this router is skipped when Exim is
+# verifying addresses. Similarly, no_expn means that this router is skipped if
+# Exim is processing an EXPN command.
+
+# If you want this router to treat local parts with suffixes introduced by "-"
+# or "+" characters as if the suffixes did not exist, uncomment the two local_
+# part_suffix options. Then, for example, xxxx-foo@your.domain will be treated
+# in the same way as xxxx@your.domain by this router. Because this router is
+# not used for verification, if you choose to uncomment those options, then you
+# will *need* to make the same change to the localuser router.  (There are
+# other approaches, if this is undesirable, but they add complexity).
+
+# The check_ancestor option means that if the forward file generates an
+# address that is an ancestor of the current one, the current one gets
+# passed on instead. This covers the case where A is aliased to B and B
+# has a .forward file pointing to A.
+
+# The three transports specified at the end are those that are used when
+# forwarding generates a direct delivery to a file, or to a pipe, or sets
+# up an auto-reply, respectively.
+
+# userforward:
+#   driver = redirect
+#   check_local_user
+# # local_part_suffix = +* : -*
+# # local_part_suffix_optional
+#   file = $home/.forward
+# # allow_filter
+#   no_verify
+#   no_expn
+#   check_ancestor
+#   file_transport = address_file
+#   pipe_transport = address_pipe
+#   reply_transport = address_reply
+
+# Virtual users/domains
+
+virtual:
+  driver = redirect
+  domains = dsearch;/etc/secrets/exim/virtual
+#  data = ''${lookup{$local_part}wildlsearch{/etc/secrets/exim/virtual/$domain}}
+  data = ''${lookup{$local_part}wildlsearch{/etc/secrets/exim/virtual/''${lookup{$domain}lsearch{/etc/secrets/exim/domains/domains}}}}
+
+my_domains:
+  driver = accept
+  domains = dsearch;/etc/secrets/exim/domains
+#  local_parts = lsearch;/etc/secrets/exim/domains/$domain
+  local_parts = lsearch;/etc/secrets/exim/domains/''${lookup{$domain}lsearch{/etc/secrets/exim/domains/domains}}
+  transport = my_mailboxes
+
+# This router matches local user mailboxes. If the router fails, the error
+# message is "Unknown user".
+
+# If you want this router to treat local parts with suffixes introduced by "-"
+# or "+" characters as if the suffixes did not exist, uncomment the two local_
+# part_suffix options. Then, for example, xxxx-foo@your.domain will be treated
+# in the same way as xxxx@your.domain by this router.
+
+localuser:
+  driver = accept
+  check_local_user
+# local_part_suffix = +* : -*
+# local_part_suffix_optional
+  transport = local_delivery
+  cannot_route_message = Unknown user
+
+
+######################################################################
+#                      TRANSPORTS CONFIGURATION                      #
+######################################################################
+#                       ORDER DOES NOT MATTER                        #
+#     Only one appropriate transport is called for each delivery.    #
+######################################################################
+
+# A transport is used only when referenced from a router that successfully
+# handles an address.
+
+begin transports
+
+# This transport is used for delivering messages over SMTP connections.
+
+remote_smtp:
+  driver = smtp
+#  hosts_require_tls = *
+  dkim_domain = $sender_address_domain
+  dkim_selector = 27112015
+  dkim_private_key = /var/lib/opendkim/keys/${opendkim_selector}.private
+  dkim_canon = relaxed
+  dkim_strict = 0
+  headers_add = X-Clacks-Overhead: "GNU Terry Pratchett"
+
+
+# This transport is used for local delivery to user mailboxes in traditional
+# BSD mailbox format. By default it will be run under the uid and gid of the
+# local user, and requires the sticky bit to be set on the /var/mail directory.
+# Some systems use the alternative approach of running mail deliveries under a
+# particular group instead of using the sticky bit. The commented options below
+# show how this can be done.
+
+# local_delivery:
+#   driver = appendfile
+#   file = /var/mail/$local_part
+#   delivery_date_add
+#   envelope_to_add
+#   return_path_add
+# # group = mail
+# # mode = 0660
+
+
+# This transport is used for handling pipe deliveries generated by alias or
+# .forward files. If the pipe generates any standard output, it is returned
+# to the sender of the message as a delivery error. Set return_fail_output
+# instead of return_output if you want this to happen only when the pipe fails
+# to complete normally. You can set different transports for aliases and
+# forwards if you want to - see the references to address_pipe in the routers
+# section above.
+
+address_pipe:
+  driver = pipe
+  return_output
+
+
+# This transport is used for handling deliveries directly to files that are
+# generated by aliasing or forwarding.
+
+address_file:
+  driver = appendfile
+  delivery_date_add
+  envelope_to_add
+  return_path_add
+
+
+# This transport is used for handling autoreplies generated by the filtering
+# option of the userforward router.
+
+address_reply:
+  driver = autoreply
+
+# Virtual users/domains
+
+my_mailboxes:
+  driver = appendfile
+  maildir_format = true
+  mode_fail_narrower = false
+  envelope_to_add = true
+  return_path_add = true
+  mode = 0600
+#  directory = /var/vmail/''${lookup{$domain}lsearch{/etc/secrets/exim/domains/domains}}/$local_part/Maildir
+  directory = /var/vmail/$domain_data/''${lookup{$local_part}dsearch{/var/vmail/$domain_data}}/Maildir
+  create_directory = true
+  user = vmail
+
+######################################################################
+#                      RETRY CONFIGURATION                           #
+######################################################################
+
+begin retry
+
+# This single retry rule applies to all domains and all errors. It specifies
+# retries every 15 minutes for 2 hours, then increasing retry intervals,
+# starting at 1 hour and increasing each time by a factor of 1.5, up to 16
+# hours, then retries every 6 hours until 4 days have passed since the first
+# failed delivery.
+
+# WARNING: If you do not have any retry rules at all (this section of the
+# configuration is non-existent or empty), Exim will not do any retries of
+# messages that fail to get delivered at the first attempt. The effect will
+# be to treat temporary errors as permanent. Therefore, DO NOT remove this
+# retry rule unless you really don't want any retries.
+
+# Address or Domain    Error       Retries
+# -----------------    -----       -------
+
+*                      *           F,2h,15m; G,16h,1h,1.5; F,4d,6h
+
+
+
+######################################################################
+#                      REWRITE CONFIGURATION                         #
+######################################################################
+
+# There are no rewriting specifications in this default configuration file.
+
+begin rewrite
+
+
+######################################################################
+#                   AUTHENTICATION CONFIGURATION                     #
+######################################################################
+
+# The following authenticators support plaintext username/password
+# authentication using the standard PLAIN mechanism and the traditional
+# but non-standard LOGIN mechanism, with Exim acting as the server.
+# PLAIN and LOGIN are enough to support most MUA software.
+#
+# These authenticators are not complete: you need to change the
+# server_condition settings to specify how passwords are verified.
+# They are set up to offer authentication to the client only if the
+# connection is encrypted with TLS, so you also need to add support
+# for TLS. See the global configuration options section at the start
+# of this file for more about TLS.
+#
+# The default RCPT ACL checks for successful authentication, and will accept
+# messages from authenticated users from anywhere on the Internet.
+
+begin authenticators
+
+# PLAIN authentication has no server prompts. The client sends its
+# credentials in one lump, containing an authorization ID (which we do not
+# use), an authentication ID, and a password. The latter two appear as
+# $auth2 and $auth3 in the configuration and should be checked against a
+# valid username and password. In a real configuration you would typically
+# use $auth2 as a lookup key, and compare $auth3 against the result of the
+# lookup, perhaps using the crypteq{}{} condition.
+
+#PLAIN:
+#  driver                     = plaintext
+#  server_set_id              = $auth2
+#  server_prompts             = :
+#  server_condition           = Authentication is not yet configured
+#  server_advertise_condition = ''${if def:tls_cipher }
+
+# plain:
+#   driver = plaintext
+#   public_name = PLAIN
+#   server_advertise_condition = ''${if eq{$tls_cipher}{}{false}{true}}
+#   server_prompts = :
+#   server_set_id = $auth2
+#   server_condition = \
+#     ''${lookup{$2}wildlsearch{/etc/mail/passwd}\
+#       {''${if crypteq{$3}{\{sha1\}''${extract{1}{:}{$value}{$value}fail}}\
+#         {yes}{no}}\
+#       }\
+#      }
+
+# LOGIN authentication has traditional prompts and responses. There is no
+# authorization ID in this mechanism, so unlike PLAIN the username and
+# password are $auth1 and $auth2. Apart from that you can use the same
+# server_condition setting for both authenticators.
+
+#LOGIN:
+#  driver                     = plaintext
+#  server_set_id              = $auth1
+#  server_prompts             = <| Username: | Password:
+#  server_condition           = Authentication is not yet configured
+#  server_advertise_condition = ''${if def:tls_cipher }
+
+# login:
+#   driver = plaintext
+#   public_name = LOGIN
+#   server_advertise_condition = ''${if eq{$tls_cipher}{}{false}{true}}
+#   server_prompts = Username:: : Password::
+#   server_set_id = $auth1
+#   server_condition = \
+#     ''${lookup{$1}wildlsearch{/etc/mail/passwd}\
+#       {''${if crypteq{$2}{\{sha1\}''${extract{1}{:}{$value}{$value}fail}}\
+#         {yes}{no}}\
+#       }\
+#      }
+
+dovecot_plain:
+  driver = dovecot
+  public_name = PLAIN
+  server_socket = /var/run/dovecot2/auth-client
+  server_set_id = $auth2
+
+
+######################################################################
+#                   CONFIGURATION FOR local_scan()                   #
+######################################################################
+
+# If you have built Exim to include a local_scan() function that contains
+# tables for private options, you can define those options here. Remember to
+# uncomment the "begin" line. It is commented by default because it provokes
+# an error with Exim binaries that are not built with LOCAL_SCAN_HAS_OPTIONS
+# set in the Local/Makefile.
+
+# begin local_scan
+
+# End of exim configuration.
+'';
+  };
+
+  security.acme.certs."smtp" = {
+    domain = "smtp.isomorphis.me";
+    extraDomainNames = [
+      "smtp.tremeg.net"
+      "smtp.gueneau.me"
+    ];
+    # group = config.services.exim.group;
+  };
+
+  # FIXME
+  system.activationScripts."secrets-permissions" = lib.mkForce ''
+    # Default to restrictive permissions on secrets.
+    # Root can alway read/write/traverse directories no matter the permissions
+    # set.
+
+    mkdir -p /etc/secrets
+
+    chown --recursive root:root /etc/secrets
+    chmod --recursive 600 /etc/secrets
+
+    # Relax permissions on some secrets.
+
+    # The top directory must be readable and traversable by thoses who need to
+    # access secrets.
+    chmod 755 /etc/secrets
+
+    mkdir -p /etc/secrets/exim/virtual
+    mkdir -p /etc/secrets/exim/domains
+    chown --recursive ${config.services.exim.user}:${config.services.exim.group} /etc/secrets/exim
+
+    mkdir -p /etc/secrets/dovecot
+    chown --recursive ${config.services.dovecot2.user}:${config.services.dovecot2.group} /etc/secrets/dovecot
+
+    # XXX
+    chmod g+r /var/lib/opendkim/keys/${opendkim_selector}.private
+  '';
+}

vars.nix

@@ -27,6 +27,13 @@
       # see ad-hoc config in oven/configuration.nix
       # Headscale RPC
       { num = 50443; proto = "tcp"; }
+      # SMTP
+      { num = 25; proto = "tcp"; }
+      { num = 465; proto = "tcp"; }
+      { num = 587; proto = "tcp"; }
+      # IMAP
+      { num = 143; proto = "tcp"; }
+      { num = 993; proto = "tcp"; }
     ];
   };