Lookup for "552 5.4.1"
Permanent Error - This status code indicates a permanent issue and is unlikely to resolve itself. You should contact the Email Service Provider.
Basic Status Code Details (552)
Requested mail action aborted: exceeded storage allocation
Enhanced Status Code Details (5.4.1)
No answer from host
The outbound connection attempt was not answered, because either the remote system was busy, or was unable to take a call. This is useful only as a persistent transient error.