diff --git a/src/yuanfen/email.py b/src/yuanfen/email.py
index 1e87496..816ec8c 100644
--- a/src/yuanfen/email.py
+++ b/src/yuanfen/email.py
@@ -53,7 +53,7 @@ def fetch(self, message_id: str, content_type: str = None):
             connection.login(self.address, self.password)
             connection.select()
             _, msg_data = connection.uid("fetch", message_id, "(RFC822)")
-            if not msg_data:
+            if not msg_data[0]:
                 return None
             raw = email.message_from_bytes(msg_data[0][1])
             mail_info = {}