diff --git a/main.py b/main.py
index 183fb50..12993f6 100644
--- a/main.py
+++ b/main.py
@@ -194,7 +194,7 @@ def mail_notify(violators: list) -> None:
             print(f'    {username} {usage_msg}')
             msg = MAIL_MESSAGE.format(username, usage_msg)
             msg = MIMEText(msg, 'html') # 郵件內文
-            msg['Subject'] = f'[網管通知] 提醒您已經超過 CMLab GPU 使用限制！({username})' + "(DEBUG MODE)" if DEBUG_MODE else ""
+            msg['Subject'] = f'[網管通知] 提醒您已經超過 CMLab GPU 使用限制！({username})'
             msg['From'] = 'unix_manager@cmlab.csie.ntu.edu.tw'
             msg['To'] = f'{username}@cmlab.csie.ntu.edu.tw' if not DEBUG_MODE else 'snsd0805@cmlab.csie.ntu.edu.tw'
             msg['Cc'] = 'unix_manager@cmlab.csie.ntu.edu.tw' if not DEBUG_MODE else 'snsd0805@cmlab.csie.ntu.edu.tw'