server settings: Add setting for MAILING_ADDRESS.

The rules here are fuzzy, and it's quite possible none of Zulip's emails
need an address at all. Every country has its own rules though, which makes
it hard to tell. In general, transactional emails do not need an address,
and marketing emails do.

templates/zerver/emails/email_base_default.source.html

@@ -33,7 +33,7 @@
                             <table border="0" cellpadding="0" cellspacing="0">
                                 <tr>
                                     <td class="content-block">
-                                        <span class="apple-link">Kandra Labs, 112 S Park St, San Francisco CA 94107</span>
+                                        <span class="apple-link">{{physical_address}}</span>
                                         {% block manage_preferences %}{% endblock %}
                                     </td>
                                 </tr>

zerver/lib/send_email.py

@@ -41,6 +41,7 @@ def build_email(template_prefix, to_user_id=None, to_email=None, from_name=None,
         'realm_name_in_notifications': False,
         'support_email': FromAddress.SUPPORT,
         'email_images_base_uri': settings.ROOT_DOMAIN_URI + '/static/images/emails',
+        'physical_address': settings.PHYSICAL_ADDRESS,
     })
     subject = loader.render_to_string(template_prefix + '.subject',
                                       context=context,

zproject/dev_settings.py

@@ -28,6 +28,7 @@ NOTIFICATION_BOT = "notification-bot@zulip.com"
 ERROR_BOT = "error-bot@zulip.com"
 NEW_USER_BOT = "new-user-bot@zulip.com"
 EMAIL_GATEWAY_BOT = "emailgateway@zulip.com"
+PHYSICAL_ADDRESS = "Zulip Headquarters, 123 Octo Stream, South Pacific Ocean"
 EXTRA_INSTALLED_APPS = ["zilencer", "analytics"]
 # Disable Camo in development
 CAMO_URI = ''

zproject/prod_settings_template.py

@@ -81,6 +81,13 @@ EMAIL_USE_TLS = True
 # zulip.example.com).
 #NOREPLY_EMAIL_ADDRESS = 'noreply@example.com'
 
+# Many countries and bulk mailers require certain types of email to display
+# a physical mailing address to comply with anti-spam legislation.
+# Non-commercial and non-public-facing installations are unlikely to need
+# this setting.
+# The address should have no newlines.
+#PHYSICAL_ADDRESS = ''
+
 ### AUTHENTICATION SETTINGS
 #
 # Enable at least one of the following authentication backends.

zproject/settings.py

@@ -115,9 +115,10 @@ else:
 # prod_settings_template.py, and in the initial /etc/zulip/settings.py on a new
 # install of the Zulip server.
 DEFAULT_SETTINGS = {
-    # Basic Django email settings
+    # Basic email settings
     'EMAIL_HOST': None,
     'NOREPLY_EMAIL_ADDRESS': "noreply@" + EXTERNAL_HOST.split(":")[0],
+    'PHYSICAL_ADDRESS': '',
 
     # Google auth
     'GOOGLE_OAUTH2_CLIENT_ID': None,