diff --git a/app/config.py b/app/config.py
index cc6e65017..ffd59304f 100644
--- a/app/config.py
+++ b/app/config.py
@@ -133,7 +133,7 @@ class Config(object):
     MAX_VERIFY_CODE_COUNT = 10
 
     MAX_LETTER_PDF_ZIP_FILESIZE = 500 * 1024 * 1024  # 500mb
-    MAX_LETTER_PDF_COUNT_PER_ZIP = 5000
+    MAX_LETTER_PDF_COUNT_PER_ZIP = 2500
 
     CHECK_PROXY_HEADER = False