Migration of always_bcc Postfix setting (#99)

* migration. always_bcc Postfix setting is retained

* mail. Add Mail archive section

- Document Always BCC field
- Add reference to/from Piler page

mail.rst

@@ -494,53 +494,81 @@ Relay settings
 --------------
 
 This section controls the Mail application configuration for special
-scenarios, described in the following points.
+scenarios, described in the following sections.
 
-1. Some old mail clients, like scanners, which provide limited software
-   capabilities, might not support SMTP authentication or encryption: in
-   this case it is possible to authorize the relay of messages to external
-   domains by looking at their IP address instead of the usual credentials
-   check.
+IP-based relay
+^^^^^^^^^^^^^^
 
-   List the IP address of such devices in the ``Allow relay from these IP
-   addresses`` field. The address can be in IPv4 or IPv6 format. The IP
-   based policy can be spread to a whole network, specifying it in CIDR
-   format.
+Some old mail clients, like scanners, which provide limited software
+capabilities, might not support SMTP authentication or encryption: in this
+case it is possible to authorize the relay of messages to external domains
+by looking at their IP address instead of the usual credentials check.
 
-   For example, a value for the field can be
+List the IP address of such devices in the ``Allow relay from these IP
+addresses`` field. The address can be in IPv4 or IPv6 format. The IP based
+policy can be spread to a whole network, specifying it in CIDR format.
 
-   ::
+For example, a value for the field can be
 
-      192.168.12.42
-      10.77.4.0/24
+::
 
-   The IP address *192.168.12.42* (e.g. a document scanner) and the
-   clients in the network subnet *10.77.4.0/24* can send mail messages
-   without providing SMTP authentication.
+  192.168.12.42
+  10.77.4.0/24
 
-2. To avoid the unauthorized use of email addresses and the sender address
-   spoofing within the organization, enable the ``Enforce sender/login
-   match`` switch.
+The IP address *192.168.12.42* (e.g. a document scanner) and the clients
+in the network subnet *10.77.4.0/24* can send mail messages without
+providing SMTP authentication.
 
-   If the switch is enabled the sender address of a message must
-   correspond to the login name used by the mail client to connect with
-   the mail server. Search the login name in the :ref:`email_addresses`
-   page to see what are the addresses it can use.
+Sender/login correspondence
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-   For example, with that switch enabled, if user ``john`` has email
-   address ``[email protected]`` he cannot write an email message with
-   a different sender address, like ``[email protected]``.
+To avoid the unauthorized use of email addresses and the sender address
+spoofing within the organization, enable the ``Enforce sender/login
+match`` switch.
 
-   If the switch is disabled, as per default Mail configuration, an
-   authenticated mail client is allowed to send messages using any sender
-   address, so back to our example ``john`` could write the message also
-   as ``[email protected]``.
+If the switch is enabled the sender address of a message must correspond
+to the login name used by the mail client to connect with the mail server.
+Search the login name in the :ref:`email_addresses` page to see what are
+the addresses it can use.
 
-   .. warning::
+For example, with that switch enabled, if user ``john`` has email address
+``[email protected]`` he cannot write an email message with a different
+sender address, like ``[email protected]``.
 
-    If you decide to enable the switch consider that public mailboxes and
-    LDAP group addresses are not evaluated for the login/address
-    correspondence.
+If the switch is disabled, as per default Mail configuration, an
+authenticated mail client is allowed to send messages using any sender
+address, so back to our example ``john`` could write the message also as
+``[email protected]``.
+
+.. warning::
+
+  If you decide to enable the switch consider that public mailboxes and
+  LDAP group addresses are not evaluated for the login/address
+  correspondence.
+
+.. _mail-archive-section:
+
+Mail archive
+^^^^^^^^^^^^
+
+The ``Always BCC`` switch controls a feature often required by mail
+archiving solutions.
+
+The acronym BCC stands for Blind Carbon Copy. When the switch is enabled,
+enter a value in the ``Always BCC address`` field: this address will
+receive a hidden copy of any email message sent or received by the Mail
+server.
+
+.. hint::
+
+  Making a hidden copy of private email messages is a privacy-sensitive
+  feature. Ensure its use complies with your country's privacy laws,
+  regulations, and company policies.
+
+The :ref:`Piler application <piler-section>` can automatically configure
+this field with the appropriate value, such as ``archive@piler1`` or similar.
+In this case, changing the address might prevent Piler from archiving new
+messages.
 
 
 .. _email_clients:

migration.rst

@@ -314,6 +314,3 @@ The following configurations will not be migrated:
 
 - System smart host, if the NS7 Email app is not installed or is not
   migrated.
-
-- In NS7 Email app, the setting ``Forward a copy of all messages``, formerly known as
-  ``Always send a copy (Bcc)``, is not migrated.

piler.rst

@@ -51,7 +51,8 @@ required fields:
      already copies any message sent or received to another archive or
      external email address. If such an entry is selected and the form is
      saved, the previous configuration is overwritten, so use it with
-     caution.
+     caution. See also the Mail :ref:`Always BCC <mail-archive-section>`
+     setting.
 
 - **Retention duration**: This field contains the number of days an email
   message is retained in the archive. After that period, a daily cron job