diff --git a/core/admin/mailu/internal/views/auth.py b/core/admin/mailu/internal/views/auth.py
index 3182188c..fed10953 100644
--- a/core/admin/mailu/internal/views/auth.py
+++ b/core/admin/mailu/internal/views/auth.py
@@ -49,7 +49,7 @@ def nginx_authentication():
         if not is_port_25:
             utils.limiter.exempt_ip_from_ratelimits(client_ip)
     elif is_valid_user:
-        password = urllib.parse.unquote(headers['Auth-Pass']) if 'Auth-Pass' in headers else ''
+        password = urllib.parse.unquote(headers.get('Auth-Pass'], None))
         utils.limiter.rate_limit_user(username, client_ip, password=password)
     elif not is_from_webmail:
         utils.limiter.rate_limit_ip(client_ip, username)