Is there an email problem with ESET Australia?

I wanted to contact ESET.com.au so I emailed them and got this response from both emails:

The original message was received at Wed, 2 Jan 2008 10:21:22 +1000
from ppp121-45-130-56.lns11.adl6.internode.on.net

----- The following addresses had permanent fatal errors -----
<sales@eset.com.au>
(expanded from: <sales@eset.com.au>)

----- Transcript of session follows -----
mail.local: unknown name: sales
550 <sales@eset.com.au>... User unknown

-

The original message was received at Wed, 2 Jan 2008 10:21:23 +1000
from ppp121-45-130-56.lns11.adl6.internode.on.net

----- The following addresses had permanent fatal errors -----
<ess_upgrade@eset.com.au>
(expanded from: <ess_upgrade@eset.com.au>)

----- Transcript of session follows -----
mail.local: unknown name: ess_upgrade
550 <ess_upgrade@eset.com.au>... User unknown


What's the deal ESET Australia?