Use hosted address for webmail sender

src/www/bongo-web.py.in

@@ -279,7 +279,12 @@ class BongoWebHandler(BaseHTTPRequestHandler):
                         self._client_ip())
 
     def _available_identities(self, owner):
-        identities = [{"address": owner, "source": "local", "label": "Bongo"}]
+        local_address = owner
+        domains = self.server.config.get("login_domains", [])
+        if "@" not in local_address and domains:
+            local_address = f"{local_address}@{domains[0]}"
+        identities = [{"address": local_address, "source": "local",
+                       "label": "Bongo"}]
         for identity in list_external_identities(owner):
             if int(identity.get("verified_at", 0)) <= 0:
                 continue
@@ -1238,6 +1243,7 @@ class BongoWebHandler(BaseHTTPRequestHandler):
             preference = self.server.identities.signature_for_sender(
                 session["user"], identity["address"])
             send_message(session["user"], data, sender=identity["address"],
+                         authenticated_address=available[0]["address"],
                          display_name=preference["display_name"],
                          signature=preference["signature"])
         except OverflowError:

src/www/bongo_web/compose.py

@@ -127,6 +127,7 @@ def build_message(sender: str, data: dict, *, display_name: str = "",
 
 
 def send_message(owner: str, data: dict, queue_factory=None, *, sender: str | None = None,
+                 authenticated_address: str | None = None,
                  display_name: str = "", signature: dict | None = None) -> None:
     """Submit a composed message to Bongo's native queue service."""
     sender = _address(sender or owner)
@@ -140,7 +141,7 @@ def send_message(owner: str, data: dict, queue_factory=None, *, sender: str | No
     try:
         queue.Create()
         created = True
-        queue.StoreFrom(_address(owner), sender)
+        queue.StoreFrom(_address(authenticated_address or owner), sender)
         for recipient in recipients:
             queue.StoreTo(recipient, recipient)
         # SMTP policy emits a seven/eight-bit clean wire representation with CRLF.

src/www/tests/test_compose.py

@@ -117,6 +117,20 @@ class ComposeTests(unittest.TestCase):
         self.assertIn("From: Alice <external@example.test>", wire_message)
         self.assertIn("-- \r\nRegards", wire_message)
 
+    def test_store_account_may_use_hosted_mail_address(self):
+        queues = []
+        def factory(user):
+            queue = FakeQueue(user)
+            queues.append(queue)
+            return queue
+        send_message("admin", {"to": "to@example.test", "text": "Hello"},
+                     factory, sender="admin@example.test",
+                     authenticated_address="admin@example.test")
+        self.assertEqual(queues[0].user, "admin")
+        self.assertEqual(queues[0].calls[1],
+                         ("StoreFrom", "admin@example.test",
+                          "admin@example.test"))
+
     def test_html_signature_is_a_multipart_alternative(self):
         message, _recipients = build_message(
             "sender@example.test",