diff --git a/src/.DS_Store b/src/.DS_Store
new file mode 100644
index 0000000..b4ed6e5
Binary files /dev/null and b/src/.DS_Store differ
diff --git a/src/fastapi_poe/base.py b/src/fastapi_poe/base.py
index 52a1ac4..d1ab536 100644
--- a/src/fastapi_poe/base.py
+++ b/src/fastapi_poe/base.py
@@ -31,6 +31,10 @@
 logger = logging.getLogger("uvicorn.default")
 
 
+class InvalidParameterError(Exception):
+    pass
+
+
 class LoggingMiddleware(BaseHTTPMiddleware):
     async def set_body(self, request: Request):
         receive_ = await request._receive()
@@ -64,7 +68,7 @@ async def dispatch(self, request: Request, call_next):
         return response
 
 
-def exception_handler(request: Request, ex: HTTPException):
+async def http_exception_handler(request, ex):
     logger.error(ex)
 
 
@@ -86,7 +90,6 @@ def auth_user(
 
 class PoeBot:
     # Override these for your bot
-
     async def get_response(
         self, request: QueryRequest
     ) -> AsyncIterable[Union[PartialResponse, ServerSentEvent]]:
@@ -111,11 +114,11 @@ def __init__(self):
         self.file_attachment_lock = asyncio.Lock()
 
     async def post_message_attachment(
-        self, message_id, file_data, filename, access_key
+        self, access_key, message_id, download_url=None, file_data=None, filename=None
     ):
         task = asyncio.create_task(
             self._make_file_attachment_request(
-                message_id, file_data, filename, access_key
+                access_key, message_id, download_url, file_data, filename
             )
         )
         async with self.file_attachment_lock:
@@ -124,19 +127,30 @@ async def post_message_attachment(
             self.pending_file_attachments[message_id] = files_for_message
 
     async def _make_file_attachment_request(
-        self, message_id, file_data, filename, access_key
+        self, access_key, message_id, download_url=None, file_data=None, filename=None
     ):
         url = "https://www.quora.com/poe_api/file_attachment_POST"
 
         async with httpx.AsyncClient(timeout=120) as client:
             try:
-                files = {"file": (filename, file_data)}
-                data = {"message_id": message_id}
                 headers = {"Authorization": f"{access_key}"}
-
-                request = httpx.Request(
-                    "POST", url, files=files, data=data, headers=headers
-                )
+                if download_url:
+                    if file_data or filename:
+                        raise InvalidParameterError(
+                            "Cannot provide filename or file_data if download_url is provided."
+                        )
+                    data = {"message_id": message_id, "download_url": download_url}
+                    request = httpx.Request("POST", url, data=data, headers=headers)
+                elif file_data and filename:
+                    data = {"message_id": message_id}
+                    files = {"file": (filename, file_data)}
+                    request = httpx.Request(
+                        "POST", url, files=files, data=data, headers=headers
+                    )
+                else:
+                    raise InvalidParameterError(
+                        "Must provide either download_url or file_data and filename."
+                    )
                 response = await client.send(request)
 
                 if response.status_code != 200:
@@ -147,15 +161,18 @@ async def _make_file_attachment_request(
                 return response
             except httpx.HTTPError:
                 logger.error("An HTTP error occurred when attempting to attach file")
+                raise
 
     async def _process_pending_attachment_requests(self, message_id):
         try:
             await asyncio.gather(*self.pending_file_attachments.get(message_id, []))
         except Exception:
             logger.error("Error processing pending attachment requests")
-        # clear the pending attachments for the message
-        async with self.file_attachment_lock:
-            self.pending_file_attachments.pop(message_id, None)
+            raise
+        finally:
+            # clear the pending attachments for the message
+            async with self.file_attachment_lock:
+                self.pending_file_attachments.pop(message_id, None)
 
     @staticmethod
     def text_event(text: str) -> ServerSentEvent:
@@ -256,7 +273,11 @@ async def handle_query(
         except Exception as e:
             logger.exception("Error responding to query")
             yield self.error_event(repr(e), allow_retry=False)
-        await self._process_pending_attachment_requests(request.message_id)
+        try:
+            await self._process_pending_attachment_requests(request.message_id)
+        except Exception as e:
+            logger.exception("Error processing pending attachment requests")
+            yield self.error_event(repr(e), allow_retry=False)
         yield self.done_event()
 
 
@@ -327,7 +348,7 @@ def make_app(
 ) -> FastAPI:
     """Create an app object. Arguments are as for run()."""
     app = FastAPI()
-    app.add_exception_handler(RequestValidationError, exception_handler)
+    app.add_exception_handler(RequestValidationError, http_exception_handler)
 
     global auth_key
     auth_key = _verify_access_key(