NNTPConnectError does still seem a slightly awkward name. I would go for NNTPConnectionError instead, but I’m also happy to put my bikeshed paint away let this patch be applied as is :)

Handling of NNTPTemporaryError with a code of 400 is similar to handling of this EOFError. But I guess there is not much you could do with the API unless you made a separate subclass for 400 errors (like all the new EnvironmentError/OSError subclasses), which would be rather severe. My current workaround looks a bit like this:

try:
    [_, info] = nntp.body(...)
except NNTPTemporaryError as err:
    [code, *msg] = err.response.split(maxsplit=1)
    if code != "400":
        raise
except EOFError:  # Or NNTPConnect(ion)Error
    msg = ()
else:
    break  # Handle successful response
[msg] = msg or ("Server shut down connection",)
# Handle connection shutdown by server