send_custom_email: Add support for emailing all admins.

This provides a convenient way to send a custom email to just the
administrators of an organization.

Fixes part of #13413.

zerver/lib/send_email.py

@@ -295,7 +295,8 @@ def send_custom_email(users: List[UserProfile], options: Dict[str, Any]) -> None
     inline_template(email_filename)
 
     # Finally, we send the actual emails.
-    for user_profile in users:
+    for user_profile in filter(lambda user:
+                               not options.get('admins_only') or user.is_realm_admin, users):
         context = {
             'realm_uri': user_profile.realm.uri,
             'realm_name': user_profile.realm.name,

zerver/management/commands/send_custom_email.py

@@ -32,6 +32,9 @@ class Command(ZulipBaseCommand):
         parser.add_argument('--reply-to',
                             type=str,
                             help='Optional reply-to line for the email')
+        parser.add_argument('--admins-only',
+                            help='Send only to organization administrators',
+                            action='store_true')
 
         self.add_user_list_args(parser,
                                 help="Email addresses of user(s) to send emails to.",

zerver/tests/test_email_notifications.py

@@ -13,7 +13,7 @@ from typing import List, Optional
 
 from zerver.lib.email_notifications import fix_emojis, handle_missedmessage_emails, \
     enqueue_welcome_emails, relative_to_full_url
-from zerver.lib.actions import do_change_notification_settings
+from zerver.lib.actions import do_change_notification_settings, do_change_is_admin
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.send_email import FromAddress, send_custom_email
 from zerver.models import (
@@ -89,6 +89,20 @@ class TestCustomEmails(ZulipTestCase):
             "from_name": from_name,
         })
 
+    def test_send_custom_email_admins_only(self) -> None:
+        admin_user = self.example_user('hamlet')
+        do_change_is_admin(admin_user, True)
+
+        non_admin_user = self.example_user('cordelia')
+
+        markdown_template_path = "zerver/tests/fixtures/email/custom_emails/email_base_headers_test.source.html"
+        send_custom_email([admin_user, non_admin_user], {
+            "markdown_template_path": markdown_template_path,
+            "admins_only": True
+        })
+        self.assertEqual(len(mail.outbox), 1)
+        self.assertIn(admin_user.delivery_email, mail.outbox[0].to[0])
+
 
 class TestFollowupEmails(ZulipTestCase):
     def test_day1_email_context(self) -> None: