email headers as "unknown" fix

[Guest]

presently, all of the emails my customers receive (sent via osc) have headers like this:

from unknown (HELO xxxx.emailserver.iam.using) ([serverip]) (envelope-sender <[email protected]>)

 

 

what contributions can fix this? (or is this a server-based setting)

i imagine, the "unknown" part could trigger a lot of spam filters?

 

i've tried: http://www.oscommerce.com/community/contributions,901/ but i didn't notice any changes in the headers.