Lookup for "535 2.5.4"
This status code indicates a successful delivery or other operation. Any details are simply notes.
Basic Status Code Details (535)
Authentication failed due to invalid or insufficient authentication credentials
Enhanced Status Code Details (2.5.4)
Invalid command arguments
A valid mail transaction protocol command was issued with invalid arguments, either because the arguments were out of range or represented unrecognized features. This is useful only as a permanent error.