diff --git a/plugins/platforms/simplex/adapter.py b/plugins/platforms/simplex/adapter.py
index 6745854d3baa0..4046ce4910ad9 100644
--- a/plugins/platforms/simplex/adapter.py
+++ b/plugins/platforms/simplex/adapter.py
@@ -830,15 +830,17 @@ class SimplexAdapter(BasePlatformAdapter):
 
         if content:
             corr_id = self._make_corr_id()
+            # Structured form: addresses by ID, and json.dumps escapes
+            # newlines + special chars correctly.  The bare @id text
+            # syntax is unreliable for DMs — the daemon silently drops
+            # messages when it cannot resolve the display name.
+            composed = json.dumps(
+                [{"msgContent": {"type": "text", "text": content}}]
+            )
             if chat_id.startswith("group:"):
-                # Structured form: addresses by numeric ID, and json.dumps
-                # escapes newlines + special chars correctly.
-                composed = json.dumps(
-                    [{"msgContent": {"type": "text", "text": content}}]
-                )
                 cmd_str = f"/_send #{chat_id[6:]} json {composed}"
             else:
-                cmd_str = f"@{chat_id} {content}"
+                cmd_str = f"/_send @{chat_id} json {composed}"
 
             await self._send_ws({"corrId": corr_id, "cmd": cmd_str})
 
diff --git a/tests/gateway/test_simplex_plugin.py b/tests/gateway/test_simplex_plugin.py
index 5a9cbc34320b6..87808f81f1bd1 100644
--- a/tests/gateway/test_simplex_plugin.py
+++ b/tests/gateway/test_simplex_plugin.py
@@ -133,6 +133,35 @@ def test_corr_id_pending_set_self_trims():
 # 7. Outbound send (mocked WS)
 # ---------------------------------------------------------------------------
 
+@pytest.mark.asyncio
+async def test_send_dm():
+    """DMs use the structured ``/_send @<id> json [...]`` form.
+
+    The bare ``@<id> text`` chat-command form is unreliable — the
+    daemon silently drops messages when it cannot resolve the display
+    name.  The structured ``/_send`` form addresses by ID and
+    survives newlines/quoting through ``json.dumps``, matching what
+    ``send_image`` and ``send_document`` already do.
+    """
+    from gateway.config import PlatformConfig
+    cfg = PlatformConfig(enabled=True, extra={"ws_url": "ws://localhost:5225"})
+    adapter = SimplexAdapter(cfg)
+
+    mock_ws = AsyncMock()
+    adapter._ws = mock_ws
+
+    result = await adapter.send("contact-42", "Hello, SimpleX!")
+    mock_ws.send.assert_called_once()
+    payload = json.loads(mock_ws.send.call_args[0][0])
+    assert payload["cmd"].startswith("/_send @contact-42 json ")
+    msg_content = json.loads(payload["cmd"].split(" json ", 1)[1])[0][
+        "msgContent"
+    ]
+    assert msg_content == {"type": "text", "text": "Hello, SimpleX!"}
+    assert payload["corrId"].startswith(_CORR_PREFIX)
+    assert result.success is True
+
+
 
 @pytest.mark.asyncio
 async def test_send_group():