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  1. <!DOCTYPE html><head><meta charset="utf-8" /><meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no" /><meta name="keywords" content="GNU, Emacs, Libre Software, Hurd, Guile, Guix" /><meta name="description" content="GNUcode.me is a website focusing on libre software projects, especially the GNU project." /><link type="application/atom+xml" rel="alternate" title="GNUcode.me -- Feed" href="/feed.xml" /><a rel="me" href="https://fosstodon.org/@thegnuguy"></a><link type="text/css" href="css/footer.min.css" rel="stylesheet"></link><link type="text/css" href="css/header.min.css" rel="stylesheet"></link><link type="text/css" href="css/main.min.css" rel="stylesheet"></link><title>Status Update May 2022 — GNUcode.me</title></head><body><header><nav><ul><li><a href="index.html">GNUcode.me</a></li><li><a href="services.html">Services</a></li><li><a href="about.html">About</a></li><li><a href="business-ideas.html">Business-ideas</a></li></ul></nav></header><h1>Status Update May 2022</h1><main><section class="basic-section-padding"><article><h3>by Joshua Branson — May 03, 2022</h3><div><p>I have worked more this month on polishing/cleaning up my currect records for
    2. 

  2. opensmtpd.  I am still finding more things to do, but I am satisified with
    3. 

  3. current code base.  It is starting to feel like I have less and less things to do.</p><p>I have also written some preleminary documentation.  The OpenBSD folks’ <code>man smtpd.conf</code>’ is a work of art.  Seriously go read it.  I have shamelessly copied
    4. 

  4. numerous portions of that documentation to create my own monstrosity.</p><p>Whoever ends up committing my code for OpenBSD’s configuration for guix, will
    5. 

  5. probably have to revise my rough draft of a document.  But at least there is
    6. 

  6. visible forward movement in the project.  Here is that documentation that I was
    7. 

  7. telling you about:</p><p>Apologies for the weird exported documentation...</p><h1>OpenSMTPD Service documentation</h1><p>OpenSMTPD is an easy-to-use mail transfer agent (MTA). Its configuration file is
    8. 

  8. throughly documented in man 5 <code>smtpd.conf</code>. OpenSMTPD <strong>listens</strong> for incoming
    9. 

  9. mail and <strong>matches</strong> the mail to <strong>actions</strong>. The following records represent those
    10. 

  10. stages: <code>&lt;opensmtpd-listen-on-configuration&gt;</code>,
    11. 

  11. <code>&lt;opensmtpd-listen-on-socket-configuration&gt;=, =&lt;opensmtpd-match-configuration&gt;</code>,
    12. 

  12. <code>&lt;opensmtpd-action-local-delivery-configuration&gt;</code>, and
    13. 

  13. <code>&lt;opensmtpd-action-relay-configuration&gt;</code>.</p><p>Additionally, each <code>&lt;opensmtpd-listen-on-configuration&gt;</code> and
    14. 

  14. <code>&lt;opensmtpd-listen-on-socket-configuration&gt;</code> may use a list of
    15. 

  15. <code>&lt;opensmtpd-filter-configuration&gt;</code>, and/or
    16. 

  16. <code>&lt;opensmtpd-filter-phase-configuration&gt;</code> records to filter email/spam. Also
    17. 

  17. numerous records’ fieldnames use <code>&lt;opensmtpd-table-configuration&gt;</code> to hold lists
    18. 

  18. or key value pairs of data.</p><p>A simple example configuration is below:</p><pre><code>(let ((smtp.gnu.org (opensmtpd-pki-configuration
    19. 

  19.                         (domain &quot;smtp.gnu.org&quot;)
    20. 

  20.                         (cert &quot;file.cert&quot;)
    21. 

  21.                         (key &quot;file.key&quot;))))
    22. 

  22.   (service opensmtpd-service-type
    23. 

  23.            (opensmtpd-configuration
    24. 

  24.             (listen-ons (list
    25. 

  25.                          (opensmtpd-listen-on-configuration
    26. 

  26.                           (pki smtp.gnu.org))
    27. 

  27.                          (opensmtpd-listen-on-configuration
    28. 

  28.                           (pki smtp.gnu.org)
    29. 

  29.                           (secure-connection &quot;smtps&quot;))))
    30. 

  30.             (matches (list
    31. 

  31.                       (opensmtpd-match-configuration
    32. 

  32.                        (action
    33. 

  33.                         (opensmtpd-action-local-delivery-configuration
    34. 

  34.                          (name &quot;local-delivery&quot;))))
    35. 

  35.                       (opensmtpd-match-configuration
    36. 

  36.                        (action
    37. 

  37.                         (opensmtpd-action-relay-configuration
    38. 

  38.                          (name &quot;relay&quot;)))))))))</code></pre><ul><li><p>Scheme Variable: opensmtpd-service-type</p><p>Service type for the OpenSMTPD (<a href="https://www.opensmtpd.org">https://www.opensmtpd.org</a>) email server. The
    39. 

  39. value for this service type is a  <code>&lt;opensmtpd-configuration&gt;</code> record.</p></li><li><p>Data Type: opensmtpd-configuration</p><p>Data type representing the configuration of OpenSMTPD.</p><ul><li><p><code>package</code> (default: <code>opensmtpd</code>)</p><p>The OpenSMTPD package to use.</p></li><li><p><code>config-file</code> (default: <code>#f</code>)</p><p>File-like object of the OpenSMTPD configuration file to use.  By default it
    40. 

  40. listens on the loopback network interface, and allows for mail from users
    41. 

  41. and daemons on the local machine, as well as permitting email to remote
    42. 

  42. servers.  Run <code>man smtpd.conf</code> for more information.</p></li><li><p><code>bounce</code> (default: <code>(list &quot;4h&quot;)</code>)</p><p><code>bounce</code> is a list of strings, which send warning messages to the envelope
    43. 

  43. sender when temporary delivery failures cause a message to remain in the
    44. 

  44. queue for longer than string &lt;span class=&quot;underline&quot;&gt;delay&lt;/span&gt;. Each string &lt;span class=&quot;underline&quot;&gt;delay&lt;/span&gt; parameter consists
    45. 

  45. of a string beginning with a positive decimal integer and a unit s, m, h,
    46. 

  46. or d. At most four delay parameters can be specified.</p></li><li><p><code>listen-ons</code> (default: <code>(list (opensmtpd-listen-on-configuration))</code> )</p><p><code>listen-ons</code> is a list of <code>&lt;opensmtpd-listen-on-configuration&gt;</code> records.
    47. 

  47. This list details what interfaces and ports OpenSMTPD listens on as well as
    48. 

  48. other information.</p></li><li><p><code>listen-on-socket</code> (default: <code>(opensmtpd-listen-on-socket-configuration-configuration)</code> )</p><p>Listens for incoming connections on the Unix domain socket.</p></li><li><p><code>includes</code> (default: <code>#f</code>)</p><p><code>includes</code> is a list of string &lt;span class=&quot;underline&quot;&gt;filenames&lt;/span&gt;. Each filename’s contents is
    49. 

  49. additional configuration that is inserted into the top of the configuration
    50. 

  50. file.</p></li><li><p><code>matches</code> default:</p><pre><code>(list (opensmtpd-match-configuration
    51. 

  51.        (action (opensmtpd-action-local-delivery-configuration
    52. 

  52.                 (name &quot;local&quot;)
    53. 

  53.                 (method &quot;mbox&quot;)))
    54. 

  54.        (for (opensmtpd-option-configuration
    55. 

  55.              (option &quot;for local&quot;))))
    56. 

  56.       (opensmtpd-match-configuration
    57. 

  57.        (action (opensmtpd-action-relay-configuration
    58. 

  58.                 (name &quot;outbound&quot;)))
    59. 

  59.        (from (opensmtpd-option-configuration
    60. 

  60.               (option &quot;from local&quot;)))
    61. 

  61.        (for (opensmtpd-option-configuration
    62. 

  62.              (option &quot;for any&quot;)))))</code></pre><p><code>matches</code> is a list of <code>&lt;opensmtpd-match-configuration&gt;</code> records, which
    63. 

  63. matches incoming mail and sends it to a correspending action. The match
    64. 

  64. records are evaluated sequentially, with the first match winning. If an
    65. 

  65. incoming mail does not match any match records, then it is rejected.</p></li><li><p><code>mta-max-deferred</code> (default: <code>100</code>)</p><p>When delivery to a given host is suspended due to temporary failures, cache
    66. 

  66. at most &lt;span class=&quot;underline&quot;&gt;number&lt;/span&gt; envelopes for that host such that they can be delivered as
    67. 

  67. soon as another delivery succeeds to that host. The default is 100.</p></li><li><p><code>queue</code> (default: <code>#f</code>)</p><p><code>queue</code> expects an <code>&lt;opensmtpd-queue-configuration&gt;</code> record. With it, one may
    68. 

  68. compress and encrypt queue-ed emails as well as set the default expiration
    69. 

  69. time for temporarily undeliverable messages.</p></li><li><p><code>smtp</code> (default: <code>#f</code>)</p><p><code>smtp</code> expects an <code>&lt;opensmtpd-smtp-configuration&gt;</code> record, which lets one
    70. 

  70. specifiy how large email may be along with other settings.</p></li><li><p><code>srs</code> (default: <code>#f</code>)</p><p><code>srs</code> expects an <code>&lt;opensmtpd-srs-configuration&gt;</code> record, which lets one set
    71. 

  71. up SRS, the Sender Rewritting Scheme.</p></li></ul></li><li><p>Data Type: opensmtpd-listen-on-configuration</p><p>Data type representing the configuration of an
    72. 

  72. <code>&lt;opensmtpd-listen-on-configuration&gt;</code>. Listen on the fieldname <code>interface</code> for
    73. 

  73. incoming connections, using the same syntax as for ifconfig(8). The interface
    74. 

  74. parameter may also be an string interface group, an string IP address, or a
    75. 

  75. string domain name. Listening can optionally be restricted to a specific
    76. 

  76. address fieldname <code>family</code>, which can be either “inet4” or “inet6”.</p><ul><li><p><code>interface</code> (default: “lo”)</p><p>The string interface to listen for incoming connections. These interface can
    77. 

  77. usually be found by the command <code>ip link</code>.</p></li><li><p><code>family</code> (default: <code>#f</code>)</p><p>The string IP family to use.  Valid strings are “inet4” or “inet6”.</p></li><li><p><code>auth</code> (default: <code>#f</code>)</p><p>Support SMTPAUTH: clients may only start SMTP transactions after successful
    78. 

  78. authentication. If <code>auth</code> is <code>#t</code>, then users are authenticated against
    79. 

  79. their own normal login credentials. Alternatively <code>auth</code> may be an
    80. 

  80. <code>&lt;opensmtpd-table-configuration&gt;</code> whose users are authenticated against
    81. 

  81. their passwords.</p></li><li><p><code>auth-optional</code> (default: <code>#f</code>)</p><p>Support SMTPAUTH optionally: clients need not authenticate, but may do so.
    82. 

  82. This allows the <code>&lt;opensmtpd-listen-on-configuration&gt;</code> to both accept
    83. 

  83. incoming mail from untrusted senders and permit outgoing mail from
    84. 

  84. authenticated users (using <code>&lt;opensmtpd-match-configuration&gt;</code> fieldname
    85. 

  85. <code>auth</code>). It can be used in situations where it is not possible to listen on
    86. 

  86. a separate port (usually the submission port, 587) for users to
    87. 

  87. authenticate.</p></li><li><p><code>filters</code> (default: <code>#f</code>)</p><p>A list of one or many <code>&lt;opensmtpd-filter-configuration&gt;</code> or
    88. 

  88. <code>&lt;opensmtpd-filter-phase-configuration&gt;</code> records. The filters are applied
    89. 

  89. sequentially. These records listen and filter on connections handled by this
    90. 

  90. listener.</p></li><li><p><code>hostname</code> (default: <code>#f</code>)</p><p>Use string “hostname” in the greeting banner instead of the default server
    91. 

  91. name.</p></li><li><p><code>hostnames</code> (default: <code>#f</code>)</p><p>Override the server name for specific addresses. Use a
    92. 

  92. <code>&lt;opensmtpd-table-configuration&gt;</code> containing a mapping of string IP
    93. 

  93. addresses to hostnames. If the address on which the connection arrives
    94. 

  94. appears in the mapping, the associated hostname is used.</p></li><li><p><code>mask-src</code> (default: <code>#f</code>)</p><p>If <code>#t</code>, then omit the from part when prepending “Received” headers.</p></li><li><p><code>disable-dsn</code> (default: <code>#f</code>)</p><p>When <code>#t</code>, then disable the DSN (Delivery Status Notification) extension.</p></li><li><p><code>pki</code> (default: <code>#f</code>)</p><p>For secure connections, use an <code>&lt;opensmtpd-pki-configuration&gt;</code>
    95. 

  95. to prove a mail server’s identity.</p></li><li><p><code>port</code> (default: <code>#f</code>)</p><p>Listen on the &lt;span class=&quot;underline&quot;&gt;integer&lt;/span&gt; port instead of the default port of 25.</p></li><li><p><code>proxy-v2</code> (default: <code>#f</code>)</p><p>If <code>#t</code>, then support the PROXYv2 protocol, rewriting appropriately source
    96. 

  96. address received from proxy.</p></li><li><p><code>received-auth</code> (default: <code>#f</code>)</p><p>If <code>#t</code>, then in “Received” headers, report whether the session was
    97. 

  97. authenticated and by which local user.</p></li><li><p><code>senders</code> (default: <code>#f</code>)</p><p>Look up the authenticated user in the supplied
    98. 

  98. <code>&lt;opensmtpd-table-configuration&gt;</code> to find the email addresses that user is
    99. 

  99. allowed to submit mail as.</p></li><li><p><code>secure-connection</code> (default: <code>#f</code>)</p><p>This is a string of one of these options:</p></li></ul></li></ul><blockquote><pre><code>   |----------------------+---------------------------------------------|
    100. 

  100.    | &quot;smtps&quot;              | Support SMTPS, by default on port 465.      |
    101. 

  101.    |----------------------+---------------------------------------------|
    102. 

  102.    | &quot;tls&quot;                | Support STARTTLS, by default on port 25.    |
    103. 

  103.    |----------------------+---------------------------------------------|
    104. 

  104.    | &quot;tls-require-verify&quot; | Like tls, but force clients to establish    |
    105. 

  105.    |                      | a secure connection before being allowed to |
    106. 

  106.    |                      | start an SMTP transaction.  With the verify |
    107. 

  107.    |                      | option, clients must also provide a valid   |
    108. 

  108.    |                      | certificate to establish an SMTP session.   |
    109. 

  109.    |----------------------+---------------------------------------------|</code></pre></blockquote><pre><code>-   `tag` (default: `#f`)
    110. 

  110.     
    111. 

  111.     Clients connecting to the listener are tagged with the given string tag.</code></pre><ul><li><p>Data Type: opensmtpd-listen-on-socket-configuration</p><p>Data type representing the configuration of an
    112. 

  112. <code>&lt;opensmtpd-listen-on-socket-configuration&gt;</code>. Listen for incoming SMTP
    113. 

  113. connections on the Unix domain socket <code>/var/run/smtpd.sock</code>. This is done by
    114. 

  114. default, even if the directive is absent.</p><ul><li><p><code>filters</code> (default: <code>#f</code>)</p><p>A list of one or many <code>&lt;opensmtpd-filter-configuration&gt;</code> or
    115. 

  115. <code>&lt;opensmtpd-filter-phase-configuration&gt;</code> records. These filter incoming
    116. 

  116. connections handled by this listener.</p></li><li><p><code>mask-src</code> (default: <code>#f</code>)</p><p>If <code>#t</code>, then omit the from part when prepending “Received” headers.</p></li><li><p><code>tag</code> (default: <code>#f</code>)</p><p>Clients connecting to the listener are tagged with the given string tag.</p></li></ul></li><li><p>Data Type: opensmtpd-match-configuration</p><p>This data type represents the configuration of an
    117. 

  117. <code>&lt;opensmtpd-match-configuration&gt;</code> record.</p><p>If at least one mail envelope matches the options of one match record, receive
    118. 

  118. the incoming message, put a copy into each matching envelope, and atomically
    119. 

  119. save the envelopes to the mail spool for later processing by the respective
    120. 

  120. <code>&lt;opensmtpd-action-configuration&gt;</code> found in fieldname <code>action</code>.</p><ul><li><p><code>action</code> (default: <code>#f</code>)</p><p>If mail matches this match configuration, then do this action. Valid values
    121. 

  121. include <code>&lt;opensmtpd-action-local-delivery-configuration&gt;</code> or
    122. 

  122. <code>&lt;opensmtpd-action-relay-configuration&gt;</code>.</p></li><li><p><code>options</code> (default: <code>#f</code>) <code>&lt;opensmtpd-option-configuration&gt;</code>
    123. 

  123. The fieldname ’option’ is a list of unique
    124. 

  124. <code>&lt;opensmtpd-option-configuration&gt;</code> records.</p><p>Each <code>&lt;opensmtpd-option-configuration&gt;</code> record’s fieldname ’option’ has some
    125. 

  125. mutually exclusive options: there can be one “for” and one “from” option.</p><p>The following matching options are supported and can all be negated via (not
    126. 

  126. #t). The options that support a table (anything surrounded with ’&lt;’ and ’&gt;’
    127. 

  127. eg: &lt;table&gt;), also support specifying regex via (regex #t).</p><ul><li><p><code>for any</code></p><p>Specify that session may address any destination.</p></li><li><p><code>for local</code></p><p>Specify that session may address any local domain.  This is the default,
    128. 

  128. and may be omitted.</p></li><li><p><code>for domain _domain_ | &lt;domain&gt;</code></p><p>Specify that session may address the string or list table &lt;span class=&quot;underline&quot;&gt;domain&lt;/span&gt;.</p></li><li><p><code>for rcpt-to _recipient_ | &lt;recipient&gt;</code></p><p>Specify that session may address the string or list table &lt;span class=&quot;underline&quot;&gt;recipient&lt;/span&gt;.</p></li><li><p><code>from any</code></p><p>Specify that session may originate from any source.</p></li><li><p><code>from auth</code></p><p>Specify that session may originate from any authenticated user, no matter
    129. 

  129. the source IP address.</p></li><li><p><code>from auth _user_ | &lt;user&gt;</code></p><p>Specify that session may originate from authenticated &lt;span class=&quot;underline&quot;&gt;user&lt;/span&gt; or user list
    130. 

  130. user, no matter the source IP address.</p></li><li><p><code>from local</code></p><p>Specify that session may only originate from a local IP address, or from
    131. 

  131. the local enqueuer.  This is the default, and may be omitted.</p></li><li><p><code>from mail-from _sender_ | &lt;sender&gt;</code></p><p>Specify that session may originate from &lt;span class=&quot;underline&quot;&gt;sender&lt;/span&gt; or table &lt;span class=&quot;underline&quot;&gt;sender&lt;/span&gt;, no
    132. 

  132. matter the source IP address.</p></li><li><p><code>from rdns</code></p><p>Specify that session may only originate from an IP address that resolves
    133. 

  133. to a reverse DNS.</p></li><li><p><code>from rdns _hostname_ | &lt;hostname&gt;</code></p><p>Specify that session may only originate from an IP address that resolves
    134. 

  134. to a reverse DNS matching string or list string &lt;span class=&quot;underline&quot;&gt;hostname&lt;/span&gt;.</p></li><li><p><code>from socket</code></p><p>Specify that session may only originate from the local enqueuer.</p></li><li><p><code>from src _address_ | &lt;address&gt;</code></p><p>Specify that session may only originate from string or list table address
    135. 

  135. which can be a specific &lt;span class=&quot;underline&quot;&gt;address&lt;/span&gt; or a subnet expressed in CIDR-notation.</p></li><li><p><code>auth</code></p><p>Matches transactions which have been authenticated.</p></li><li><p><code>auth _username_ | &lt;username&gt;</code></p><p>Matches transactions which have been authenticated for user or user list
    136. 

  136. &lt;span class=&quot;underline&quot;&gt;username&lt;/span&gt;.</p></li><li><p><code>helo _helo-name_ | &lt;helo-name&gt;</code></p><p>Specify that session’s HELO / EHLO should match the string or list table
    137. 

  137. &lt;span class=&quot;underline&quot;&gt;helo-name&lt;/span&gt;.</p></li><li><p><code>mail-from _sender_ | &lt;sender&gt;</code></p><p>Specify that transactions’s MAIL FROM should match the string or list
    138. 

  138. table &lt;span class=&quot;underline&quot;&gt;sender&lt;/span&gt;.</p></li><li><p><code>rcpt-to _recipient_ | &lt;recipient&gt;</code></p><p>Specify that transaction’s RCPT TO should match the string or list table
    139. 

  139. &lt;span class=&quot;underline&quot;&gt;recipient&lt;/span&gt;.</p></li><li><p><code>tag tag</code>
    140. 

  140. Matches transactions tagged with the given &lt;span class=&quot;underline&quot;&gt;tag&lt;/span&gt;.</p></li><li><p><code>tls</code>
    141. 

  141. Specify that transaction should take place in a TLS channel.</p></li></ul><p>Here is a simple example:</p><pre><code>(opensmtpd-option-configuration
    142. 

  142.  (not #t)
    143. 

  143.  (regex #f)
    144. 

  144.  (option &quot;for domain&quot;)
    145. 

  145.  (data (opensmtpd-table-configuration
    146. 

  146.         (name &quot;domain-table&quot;)
    147. 

  147.         (data (list &quot;gnu.org&quot; &quot;dismail.de&quot;)))))</code></pre><p>The mail must NOT come from the domains <code>gnu.org</code> or <code>dismail.de</code>.</p></li><li><p>Data Type: opensmtpd-option-configuration</p></li></ul></li><li><p>Data Type: opensmtpd-action-local-delivery-configuration</p><p>This data type represents the configuration of an
    148. 

  148. <code>&lt;opensmtpd-action-local-delivery-configuration&gt;</code> record.</p><ul><li><p><code>name</code> (default: <code>#f</code>)</p><p><code>name</code> is the string name of the relay action.</p></li><li><p><code>method</code> (default: <code>&quot;mbox&quot;</code>)</p><p>The email delivery option.  Valid options are:</p><ul><li><p><code>&quot;mbox&quot;</code></p><p>Deliver the message to the user’s mbox with mail.local(8).</p></li><li><p><code>&quot;expand-only&quot;</code></p><p>Only accept the message if a delivery method was specified in an aliases
    149. 

  149. or &lt;span class=&quot;underline&quot;&gt;.forward file&lt;/span&gt;.</p></li><li><p><code>&quot;forward-only&quot;</code></p><p>Only accept the message if the recipient results in a remote address after
    150. 

  150. the processing of aliases or forward file.</p></li><li><p><code>&lt;opensmtpd-lmtp-configuration&gt;</code></p><p>Deliver the message to an LMTP server at
    151. 

  151. <code>&lt;opensmtpd-lmtp-configuration&gt;</code>’s fieldname <code>destination</code>. The location
    152. 

  152. may be expressed as string host:port or as a UNIX socket. Optionally,
    153. 

  153. <code>&lt;opensmtpd-lmtp-configuration&gt;</code>’s fieldname <code>rcpt-to</code> might be specified
    154. 

  154. to use the recipient email address (after expansion) instead of the local
    155. 

  155. user in the LMTP session as RCPT TO.</p></li><li><p><code>&lt;opensmtpd-maildir-configuration&gt;</code></p><p>Deliver the message to the maildir in
    156. 

  156. <code>&lt;opensmtpd-maildir-configuration&gt;</code>’s fieldname <code>pathname</code> if specified,
    157. 

  157. or by default to <code>~/Maildir</code>.</p><p>The pathname may contain format specifiers that are expanded before use
    158. 

  158. (see the below section about Format Specifiers).</p><p>If <code>&lt;opensmtpd-maildir-configuration&gt;</code>’s record fieldname <code>junk</code> is <code>#t</code>,
    159. 

  159. then message will be moved to the ‘Junk’ folder if it contains a positive
    160. 

  160. ‘X-Spam’ header. This folder will be created under fieldname <code>pathname</code> if
    161. 

  161. it does not yet exist.</p></li><li><p><code>&lt;opensmtpd-mda-configuration&gt;</code></p><p>Delegate the delivery to the <code>&lt;opensmtpd-mda-configuration&gt;</code>’s fieldname
    162. 

  162. <code>command</code> (type string) that receives the message on its standard input.</p><p>The <code>command</code> may contain format specifiers that are expanded before use
    163. 

  163. (see Format Specifiers).</p></li></ul></li><li><p><code>alias</code> (default: <code>#f</code>)</p><p>Use the mapping table for aliases expansion. <code>alias</code> is an
    164. 

  164. <code>&lt;opensmtpd-table-configuration&gt;</code>.</p></li><li><p><code>ttl</code> (default: <code>#f</code>)</p><p><code>ttl</code> is a string specify how long a message may remain in the queue.  It’s
    165. 

  165. format is <code>n{s|m|h|d}</code>.  eg: “4m” is four minutes.</p></li><li><p><code>user</code> (default: <code>#f</code> )</p><p><code>user</code> is the string username for performing the delivery, to be looked up
    166. 

  166. with getpwnam(3).</p><p>This is used for virtual hosting where a single username is in charge of
    167. 

  167. handling delivery for all virtual users.</p><p>This option is not usable with the mbox delivery method.</p></li><li><p><code>userbase</code> (default: <code>#f</code>)</p><p><code>userbase</code> is an <code>&lt;opensmtpd-table-configuration&gt;</code> record for mapping user
    168. 

  168. lookups instead of the getpwnam(3) function.</p><p>The fieldnames <code>user</code> and <code>userbase</code> are mutually exclusive.</p></li><li><p><code>virtual</code> (default: <code>#f</code>)</p><p><code>virtual</code> is an <code>&lt;opensmtpd-table-configuration&gt;</code> record is used for virtual
    169. 

  169. expansion.</p></li></ul></li><li><p>Data Type: opensmtpd-action-relay-configuration</p><p>This data type represents the configuration of an
    170. 

  170. <code>&lt;opensmtpd-action-relay-configuration&gt;</code> record.</p><ul><li><p><code>name</code> (default: <code>#f</code>)</p><p><code>name</code> is the string name of the relay action.</p></li><li><p><code>backup</code> (default: <code>#f</code>)</p><p>When <code>#t</code>, operate as a backup mail exchanger delivering messages to any
    171. 

  171. mail exchanger with higher priority.</p></li><li><p><code>backup-mx</code> (default: <code>#f</code>)</p><p>Operate as a backup mail exchanger delivering messages to any mail exchanger
    172. 

  172. with higher priority than mail exchanger identified as string name.</p></li><li><p><code>helo</code> (default: <code>#f</code>)</p><p>Advertise string heloname as the hostname to other mail exchangers during
    173. 

  173. the HELO phase.</p></li><li><p><code>helo-src</code> (default: <code>#f</code> )</p><p>Use the mapping <code>&lt;openmstpd-table-configuration&gt;</code> to look up a hostname
    174. 

  174. matching the source address, to advertise during the HELO phase.</p></li><li><p><code>domain</code> (default: <code>#f</code>)</p><p>Do not perform MX lookups but look up destination domain in an
    175. 

  175. <code>&lt;opensmtpd-table-configuration&gt;</code> and use matching relay url as relay host.</p></li><li><p><code>host</code> (default: <code>#f</code>)</p><p>Do not perform MX lookups but relay messages to the relay host described by
    176. 

  176. the string relay-url. The format for relay-url is
    177. 

  177. <code>[proto://[label@]]host[:port]</code>. The following protocols are available:</p><p>Unless noted, port defaults to 25.</p><p>The label corresponds to an entry in a credentials table, as documented in
    178. 

  178. <code>table(5)</code>. It is used with the <code>&quot;smtp+tls&quot;</code> and <code>&quot;smtps&quot;</code> protocols for
    179. 

  179. authentication. Server certificates for those protocols are verified by
    180. 

  180. default.</p></li><li><p><code>pki</code> (default: <code>#f</code>)</p><p>For secure connections, use the certificate associated with
    181. 

  181. <code>&lt;opensmtpd-pki-configuration&gt;</code> (declared in a pki directive) to prove the
    182. 

  182. client’s identity to the remote mail server.</p></li><li><p><code>srs</code> (default: <code>#f</code>)</p><p>If <code>#t</code>, then when relaying a mail resulting from a forward, use the Sender
    183. 

  183. Rewriting Scheme to rewrite sender address.</p></li><li><p><code>tls</code> (default: <code>#f</code>) boolean or string “no-verify”</p><p>When <code>#t</code>, Require TLS to be used when relaying, using mandatory STARTTLS by
    184. 

  184. default. When used with a smarthost, the protocol must not be
    185. 

  185. <code>&quot;smtp+notls://&quot;</code>. When string <code>&quot;no-verify&quot;</code>, then do not require a valid
    186. 

  186. certificate.</p></li><li><p><code>auth</code> (default: <code>#f</code>) <code>&lt;opensmtpd-table-configuration&gt;</code></p><p>Use the alist <code>&lt;opensmtpd-table-configuration&gt;</code> for connecting to relay-url
    187. 

  187. using credentials. This option is usable only with fieldname <code>host</code> option.</p></li><li><p><code>mail-from</code> (default: <code>#f</code>) string</p><p>Use the string &lt;span class=&quot;underline&quot;&gt;mailaddress&lt;/span&gt; as MAIL FROM address within the SMTP transaction.</p></li><li><p><code>src</code> (default: <code>#f</code>) string | <code>&lt;opensmtpd-table-configuration&gt;</code></p><p>Use the string or <code>&lt;opensmtpd-table-configuration&gt;</code> sourceaddr for the
    188. 

  188. source IP address, which is useful on machines with multiple interfaces. If
    189. 

  189. the list contains more than one address, all of them are used in such a way
    190. 

  190. that traffic is routed as efficiently as possible.</p></li></ul></li><li><p>Data Type: opensmtpd-filter-configuration</p><p>This data type represents the configuration of an
    191. 

  191. <code>&lt;opensmtpd-filter-configuration&gt;</code>. This is the filter record one should use
    192. 

  192. if they want to use an external package to filter email eg: rspamd or
    193. 

  193. spamassassin.</p><ul><li><p><code>name</code> (default: <code>#f</code>)</p><p>The string name of the filter.</p></li><li><p><code>proc</code> (default: <code>#f</code>)</p><p>The string command or process name.  If <code>proc-exec</code> is <code>#t</code>, <code>proc</code> is
    194. 

  194. treated as a command to execute.  Otherwise, it is a process name.</p></li><li><p><code>proc-exec</code> (default: <code>#f</code>)</p></li></ul></li><li><p>Data Type: opensmtpd-filter-phase-configuration</p><p>This data type represents the configuration of an
    195. 

  195. <code>&lt;opensmtpd-filter-phase-configuration&gt;</code>.</p><p>In a regular workflow, smtpd(8) may accept or reject a message based only on
    196. 

  196. the content of envelopes. Its decisions are about the handling of the message,
    197. 

  197. not about the handling of an active session.</p><p>Filtering extends the decision making process by allowing smtpd(8) to stop at
    198. 

  198. each phase of an SMTP session, check that options are met, then decide if a
    199. 

  199. session is allowed to move forward.</p><p>With filtering via an <code>&lt;opensmtpd-filter-phase-configuration&gt;</code> record, a
    200. 

  200. session may be interrupted at any phase before an envelope is complete. A
    201. 

  201. message may also be rejected after being submitted, regardless of whether the
    202. 

  202. envelope was accepted or not.</p><ul><li><p><code>name</code> (default: <code>#f</code>)</p><p>The string name of the filter phase.</p></li><li><p><code>phase-name</code> (default: <code>#f</code>)</p><p>The string name of the phase. Valid values are:</p></li></ul></li></ul><pre><code>-   `options` (default `#f`)
    203. 

  203.     
    204. 

  204.     A list of unique `&lt;opensmtpd-option-configuration&gt;` records.
    205. 

  205.     
    206. 

  206.     At each phase, various options, specified by a list of
    207. 

  207.     `&lt;opensmtpd-option-configuration&gt;`, may be checked. The
    208. 

  208.     `&lt;opensmtpd-option-configuration&gt;`&amp;rsquo;s fieldname &amp;rsquo;option&amp;rsquo; values of: &amp;ldquo;fcrdns&amp;rdquo;,
    209. 

  209.     &amp;ldquo;rdns&amp;rdquo;, and &amp;ldquo;src&amp;rdquo; data are available in all phases, but other data must have
    210. 

  210.     been already submitted before they are available. Options with a `&lt;table&gt;`
    211. 

  211.     next to them require the `&lt;opensmtpd-option-configuration&gt;`&amp;rsquo;s fieldname
    212. 

  212.     `data` to be an `&lt;opensmtpd-table-configuration&gt;`. There are the available
    213. 

  213.     options:
    214. 

  214.     
    215. 

  215.     
    216. 

  216.     These conditions may all be negated by setting
    217. 

  217.     `&lt;opensmtpd-option-configuration&gt;`&amp;rsquo;s fieldname `not` to `#t`.
    218. 

  218.     
    219. 

  219.     Any conditions that require a table may indicate that tables include regexs
    220. 

  220.     setting `&lt;opensmtpd-option-configuration&gt;`&amp;rsquo;s fieldname `regex` to `#t`.
    221. 

  221. 

  222. -   `decision`
    223. 

  223.     
    224. 

  224.     A string decision to be taken. Some decisions require an `message` or
    225. 

  225.     `value`. Valid strings are:
    226. 

  226.     
    227. 

  227.     Decisions that involve a message require that the message be RFC valid,
    228. 

  228.     meaning that they should either start with a 4xx or 5xx status code.
    229. 

  229.     Descisions can be taken at any phase, though junking can only happen before
    230. 

  230.     a message is committed.
    231. 

  231. 

  232. -   `message` (default `#f`)
    233. 

  233.     
    234. 

  234.     A string message beginning with a 4xx or 5xx status code.
    235. 

  235. 

  236. -   `value` (default: `#f`)
    237. 

  237.     
    238. 

  238.     A number value.  `value` and `message` are mutually exclusive.</code></pre><ul><li><p>Data Type: opensmtpd-option-configuration</p><p>This data type represents the configuration of an
    239. 

  239. <code>&lt;opensmtpd-option-configuration&gt;</code>, which is used by
    240. 

  240. <code>&lt;opensmtpd-filter-phase-configuration&gt;</code> and <code>&lt;opensmtpd-match-configuration&gt;</code>
    241. 

  241. to match various options for email.</p><ul><li><p><code>conditition</code> (default <code>#f</code>)</p><p>A string option to be taken. Some options require a string or an
    242. 

  242. <code>&lt;opensmtpd-table-configuration&gt;</code> via the fieldname data. When the option
    243. 

  243. record is used inside of an <code>&lt;opensmtpd-filter-phase-configuration&gt;</code>, then
    244. 

  244. valid strings are:</p><p>At each phase, various options may be matched. The fcrdns, rdns, and src
    245. 

  245. data are available in all phases, but other data must have been already
    246. 

  246. submitted before they are available.</p></li></ul></li></ul><pre><code>    When `&lt;opensmtpd-option-configuration&gt;` is used inside of an
    247. 

  247.     `&lt;opensmtpd-match-configuration&gt;`, then valid strigs for fieldname `option`
    248. 

  248.     are: &amp;ldquo;for&amp;rdquo;, &amp;ldquo;for any&amp;rdquo;, &amp;ldquo;for local&amp;rdquo;, &amp;ldquo;for domain&amp;rdquo;, &amp;ldquo;for rcpt-to&amp;rdquo;, &amp;ldquo;from any&amp;rdquo;
    249. 

  249.     &amp;ldquo;from auth&amp;rdquo;, &amp;ldquo;from local&amp;rdquo;, &amp;ldquo;from mail-from&amp;rdquo;, &amp;ldquo;from rdns&amp;rdquo;, &amp;ldquo;from socket&amp;rdquo;,
    250. 

  250.     &amp;ldquo;from src&amp;rdquo;, &amp;ldquo;auth&amp;rdquo;, &amp;ldquo;helo&amp;rdquo;, &amp;ldquo;mail-from&amp;rdquo;, &amp;ldquo;rcpt-to&amp;rdquo;, &amp;ldquo;tag&amp;rdquo;, or &amp;ldquo;tls&amp;rdquo;.
    251. 

  251. 

  252. -   `data` (default `#f`) `&lt;opensmtpd-table-configuration&gt;`
    253. 

  253.     
    254. 

  254.     Some options require a table to be present. One would specify that table
    255. 

  255.     here.
    256. 

  256. -   `regex` (default: `#f`) boolean
    257. 

  257.     
    258. 

  258.     Any options using a table may indicate that tables hold regex by
    259. 

  259.     prefixing the table name with the keyword regex.
    260. 

  260. -   `not` (default: `#f`) boolean
    261. 

  261.     
    262. 

  262.     When `#t`, this option record is negated.</code></pre><ul><li><p>Data Type: opensmtpd-table-configuration</p><p>This data type represents the configuration of an
    263. 

  263. <code>&lt;opensmtpd-table-configuration&gt;</code>.</p><ul><li><p><code>name</code> (default <code>#f</code>)</p><p><code>name</code> is the name of the <code>&lt;opensmtpd-table-configuration&gt;</code> record.</p></li><li><p><code>data</code> (default: <code>#f</code>)</p><p><code>data</code> expects a list of strings or an alist, which is a list of
    264. 

  264. cons cells.  eg: <code>(data (list (&quot;james&quot; . &quot;password&quot;)))</code> OR
    265. 

  265. <code>(data (list (&quot;gnu.org&quot; &quot;fsf.org&quot;)))</code>.</p></li></ul></li><li><p>Data Type: opensmtpd-pki-configuration</p><p>This data type represents the configuration of an
    266. 

  266. <code>&lt;opensmtpd-pki-configuration&gt;</code>.</p><ul><li><p><code>domain</code> (default <code>#f</code>)</p><p><code>domain</code> is the string name of the <code>&lt;opensmtpd-pki-configuration&gt;</code> record.</p></li><li><p><code>cert</code> (default: <code>#f</code>)</p><p><code>cert</code> (default: <code>#f</code>)</p><p><code>cert</code> is the string certificate filename to use for this pki.</p></li><li><p><code>key</code> (default: <code>#f</code>)</p><p><code>key</code> is the string certificate falename to use for this pki.</p></li><li><p><code>dhe</code> (default: <code>&quot;none&quot;</code>)</p><p>Specify the DHE string parameter to use for DHE cipher suites with host
    267. 

  267. pkiname. Valid parameter values are “none”, “legacy”, or “auto”. For “legacy”, a
    268. 

  268. fixed key length of 1024 bits is used, whereas for “auto”, the key length is
    269. 

  269. determined automatically. The default is “none”, which disables DHE cipher
    270. 

  270. suites.</p></li></ul></li><li><p>Data Type: opensmtpd-maildir-configuration</p><ul><li><p><code>pathname</code> (default: <code>&quot;~/Maildir&quot;</code>)</p><p>Deliver the message to the maildir if pathname if specified, or by default
    271. 

  271. to <code>~/Maildir</code>.</p><p>The pathname may contain format specifiers that are expanded before use
    272. 

  272. (see FORMAT SPECIFIERS).</p></li><li><p><code>junk</code> (default: <code>#f</code>)</p><p>If the junk argument is <code>#t</code>, then the message will be moved to the <code>‘Junk’</code>
    273. 

  273. folder if it contains a positive <code>‘X-Spam’</code> header. This folder will be
    274. 

  274. created under pathname if it does not yet exist.</p></li></ul></li><li><p>Data Type: opensmtpd-mda-configuration</p><ul><li><p><code>name</code></p><p>The string name for this MDA command.</p></li><li><p><code>command</code></p><p>Delegate the delivery to a command that receives the message on its standard
    275. 

  275. input.</p><p>The command may contain format specifiers that are expanded before use (see
    276. 

  276. FORMAT SPECIFIERS).</p></li></ul></li><li><p>Data Type: opensmtpd-queue-configuration</p><ul><li><p><code>compression</code> (default <code>#f</code>)</p><p>Store queue files in a compressed format. This may be useful to save disk
    277. 

  277. space.</p></li><li><p><code>encryption</code> (default <code>#f</code>)</p><p>Encrypt queue files with EVP&lt;sub&gt;aes&lt;/sub&gt;&lt;sub&gt;256&lt;/sub&gt;&lt;sub&gt;gcm&lt;/sub&gt;(3). If no key is specified, it is
    278. 

  278. read with getpass(3). If the string stdin or a single dash (‘-’) is given
    279. 

  279. instead of a key, the key is read from the standard input.</p></li><li><p><code>ttl-delay</code> (default <code>#f</code>)</p><p>Set the default expiration time for temporarily undeliverable messages,
    280. 

  280. given as a positive decimal integer followed by a unit s, m, h, or d. The
    281. 

  281. default is four days (“4d”).</p></li></ul></li><li><p>Data Type: opensmtpd-smtp-configuration</p><p>Data type representing an <code>&lt;opensmtpd-smtp-configuration&gt;</code> record.</p><ul><li><p><code>ciphers</code> (default: <code>#f</code>)</p><p>Set the control string for SSL&lt;sub&gt;CTX&lt;/sub&gt;&lt;sub&gt;set&lt;/sub&gt;&lt;sub&gt;cipher&lt;/sub&gt;&lt;sub&gt;list&lt;/sub&gt;(3).  The default is
    282. 

  282. “HIGH:!aNULL:!MD5”.</p></li><li><p><code>limit-max-mails</code> (default: <code>100</code>)</p><p>Limit the number of messages to count for each sessio</p></li><li><p><code>limit-max-rcpt</code> (default: <code>1000</code>)</p><p>Limit the number of recipients to count for each transaction.</p></li><li><p><code>max-message-size</code> (default: <code>35M</code>)</p><p>Reject messages larger than size, given as a positive number of bytes or as
    283. 

  283. a string to be parsed with scan&lt;sub&gt;scaled&lt;/sub&gt;(3).</p></li><li><p><code>sub-addr-delim character</code> (default: <code>+</code>)</p><p>When resolving the local part of a local email address, ignore the ASCII
    284. 

  284. character and all characters following it. This is helpful for email
    285. 

  285. filters. <code>&quot;admin+bills@gnu.org&quot;</code> is the same email address as
    286. 

  286. <code>&quot;admin@gnu.org&quot;</code>. BUT an email filter can filter emails addressed to first
    287. 

  287. email address into a ’Bills’ email folder.</p></li></ul></li><li><p>Data Type: opensmtpd-srs-configuration</p><ul><li><p><code>key</code> (default: <code>#f</code>)</p><p>Set the secret key to use for SRS, the Sender Rewriting Scheme.</p></li><li><p><code>backup-key</code> (default: <code>#f</code>)</p><p>Set a backup secret key to use as a fallback for SRS. This can be used to
    288. 

  288. implement SRS key rotation.</p></li><li><p><code>ttl-delay</code> (default: <code>&quot;4d&quot;</code>)</p><p>Set the time-to-live delay for SRS envelopes. After this delay, a bounce
    289. 

  289. reply to the SRS address will be discarded to limit risks of forged
    290. 

  290. addresses.</p></li></ul></li><li><p>Format Specifiers</p><p>Some configuration records support expansion of their parameters at
    291. 

  291. runtime. Such records (for example
    292. 

  292. <code>&lt;opensmtpd-maildir-configuration&gt;</code>, <code>&lt;opensmtpd-mda-configuration&gt;</code>) may use
    293. 

  293. format specifiers which are expanded before delivery or relaying. The
    294. 

  294. following formats are currently supported:</p></li></ul><pre><code>Expansion formats also support partial expansion using the optional bracket notations
    295. 

  295. with substring offset.  For example, with recipient domain `“example.org”`:
    296. 

  296. 

  297. 

  298. In addition, modifiers may be applied to the token.  For example, with recipient
    299. 

  299. `“User+Tag@Example.org”`:</code></pre></div></article></section></main><footer><p>© 2020 Joshua Branson.  The text on this site is free culture under the Creative Commons Attribution Share-Alike 4.0 International license.</p><p>This website is build with Haunt, a static site generator written in Guile Scheme.  Source code is <a href="https://notabug.org/jbranso/gnucode.me">available.</a></p><p>The color theme of this website is based off of the famous <a href="#3f3f3f" target="_blank">zenburn</a> theme.</p></footer></body>
    300.