diff --git a/tools/mail.py b/tools/mail.py
index 37948846..ab54b750 100755
--- a/tools/mail.py
+++ b/tools/mail.py
@@ -103,4 +103,5 @@ elif sys.argv[1] == "alias" and sys.argv[2] == "remove" and len(sys.argv) == 4:
 
 else:
 	print("Invalid command-line arguments.")
+	sys.exit(1)