fix: process one queued email per poll cycle to keep callbacks responsive

main.py

@@ -107,24 +107,24 @@ def _tg_worker(cfg):
         except Exception as e:
             logger.error(f"TG 轮询错误: {e}", exc_info=True)
 
-        while _running:
+        # 每轮只处理一封待发邮件，然后立刻回去 poll Telegram
+        try:
+            info = _tg_queue.get_nowait()
+            tg_send_and_mark(cfg, info)
+            uid_str = info["uid"].decode("utf-8", errors="replace") if isinstance(info["uid"], bytes) else str(info["uid"])
+            mark_sent(uid_str)
+        except queue_module.Empty:
+            pass
+        except Exception as e:
+            logger.error(f"TG 发送失败: {e}", exc_info=True)
             try:
-                info = _tg_queue.get_nowait()
-                tg_send_and_mark(cfg, info)
                 uid_str = info["uid"].decode("utf-8", errors="replace") if isinstance(info["uid"], bytes) else str(info["uid"])
-                mark_sent(uid_str)
-            except queue_module.Empty:
-                break
-            except Exception as e:
-                logger.error(f"TG 发送失败: {e}", exc_info=True)
-                try:
-                    uid_str = info["uid"].decode("utf-8", errors="replace") if isinstance(info["uid"], bytes) else str(info["uid"])
-                    mark_failed(uid_str)
-                except Exception:
-                    pass
+                mark_failed(uid_str)
+            except Exception:
+                pass
 
         if _running:
-            _shutdown_event.wait(1)
+            _shutdown_event.wait(0.2)
 
 
 def main():