[AusNOG] Contacts in hanmail.net/Daum Communications?

[Paul Gear]

Hi folks,

I apologise if this is a little off topic for the list, but i'm at a
loss as to how i can tackle it, so i'm hoping for some pointers.

One of my clients has been blocked from sending email to hanmail.net by
hanmail's spam filter.  There is no reason given or troubleshooting URL
given like there is in many commercial and open source email filters. 
I've reviewed their anti-spam page at http://hmm.daum.net/nospam/ and
there doesn't appear to be any problem in our setup which matches any of
their criteria.  I've checked a couple of the common reputation filters
like senderbase.org and barracudacentral.org and our IP range is not
listed there, so all i can really tell the client is, "They're blocking
your email."

It appears that there is no English version of hanmail, and apparently
you need a Korean social security number to sign up (!), so i can't even
sign up for a test account and troubleshoot from the user perspective. 
Can anyone offer suggestions as to how to communicate effectively with
companies like this (given that i can't email them)?

Thanks,
Paul