email: Implement adding common aliases for first admin user

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/email/__init__.py

@@ -9,7 +9,7 @@ from django.urls import reverse_lazy
 from django.utils.translation import gettext_lazy as _
 
 import plinth.app
-from plinth import actions, frontpage, menu
+from plinth import actions, cfg, frontpage, menu
 from plinth.daemon import Daemon
 from plinth.modules.apache.components import Webserver
 from plinth.modules.backups.components import BackupRestore
@@ -18,14 +18,22 @@ from plinth.modules.firewall.components import Firewall
 from plinth.modules.letsencrypt.components import LetsEncrypt
 from plinth.package import Packages, remove
 from plinth.signals import domain_added, domain_removed
+from plinth.utils import format_lazy
 
-from . import manifest, privileged
+from . import aliases, manifest, privileged
 
 _description = [
     _('This is a complete email server solution using Postfix, Dovecot, '
       'and Rspamd. Postfix sends and receives emails. Dovecot allows '
       'email clients to access your mailbox using IMAP and POP3. Rspamd deals '
       'with spam.'),
+    format_lazy(
+        _('Each user on {box_name} gets an email address like '
+          'user@mydomain.example. They will also receive mail from all '
+          'addresses that look like user+foo@mydomain.example. Further, '
+          'they can add aliases to their email address. Necessary aliases '
+          'such as "postmaster" are automatically created pointing to the '
+          'first admin user.'), box_name=_(cfg.box_name)),
     _('<a href="/plinth/apps/roundcube/">Roundcube app</a> provides web '
       'interface for users to access email.'),
     _('During installation, any other email servers in the system will be '
@@ -160,6 +168,13 @@ def get_domains():
     return [default_domain] if default_domain else []
 
 
+def _get_first_admin():
+    """Return an admin user in the system or None if non exist."""
+    from django.contrib.auth.models import User
+    users = User.objects.filter(groups__name='admin')
+    return users[0].username if users else None
+
+
 def setup(helper, old_version=None):
     """Installs and configures module"""
 
@@ -181,6 +196,7 @@ def setup(helper, old_version=None):
     app.get_component('letsencrypt-email-dovecot').setup_certificates()
     helper.call('post', privileged.domain.set_domains)
     helper.call('post', privileged.postfix.setup)
+    helper.call('post', aliases.setup_common_aliases, _get_first_admin())
     helper.call('post', privileged.spam.setup)
 
     # Restart daemons

plinth/modules/email/aliases.py

@@ -89,3 +89,18 @@ COMMIT;
 '''
     with _get_cursor() as cursor:
         cursor.executescript(query)
+
+
+def setup_common_aliases(username):
+    """Create aliases for common mailboxes described in RFC2142.
+
+    See: https://datatracker.ietf.org/doc/html/rfc2142
+    """
+    aliases = [
+        'mailer-daemon', 'postmaster', 'nobody', 'webmaster', 'www',
+        'hostmaster', 'info', 'support', 'abuse', 'noc', 'security'
+        'usenet', 'news', 'ftp'
+    ]
+    for alias in aliases:
+        if not exists(alias):
+            put(username, alias)

plinth/modules/email/privileged/postfix.py

@@ -75,6 +75,9 @@ def _setup_alias_maps():
     alias_maps = postconf.get_config(['alias_maps'])['alias_maps']
     alias_maps = alias_maps.replace(',', ' ').split(' ')
     if SQLITE_ALIASES not in alias_maps:
-        alias_maps.append(SQLITE_ALIASES)
+        # Prioritize FreedomBox's sqlite based aliases file over /etc/aliases.
+        # Otherwise, the common aliases will be pointing to 'root' instead of
+        # first admin user (which is more practical in FreedomBox).
+        alias_maps = [SQLITE_ALIASES] + alias_maps
 
     postconf.set_config({'alias_maps': ' '.join(alias_maps)})