Lookup for "211 4.4.1"
Temporary Error - This status code indicates a transient issue and may resolve itself.
Basic Status Code Details (211)
System status, or system help reply
Enhanced Status Code Details (4.4.1)
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.