Lookup for "553 4.5.4"
Temporary Error - This status code indicates a transient issue and may resolve itself.
Basic Status Code Details (553)
Requested action not taken: mailbox name not allowed [E.g., mailbox syntax incorrect]
Enhanced Status Code Details (4.5.4)
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.