[SpamCop-List] Why does this show up so often in forged spam email?

[Geoffrey Hyde]

extmail.bpbb.bigpond.com

I've been watching the spam headers for a while now, and I'm getting curious 
as to why the spammers are getting away with misuse of this domain name 
this, and if there is any sort of anti-spam protection that bigpond could 
employ against faked header names.

Just how much additional processing time is it for the mailserver to reject 
at the transaction stage a bad or mismatched IP address purporting to be 
from one of their own servers?

I have once or twice seen bigpond insert 'really [insert server name 
here]' - does this mean anything?

Lastly, does anyone know if bigpond are considered blackhat, whitehat, or 
unknown?


Cheers ...

Geoffrey Hyde