Thanks for your offer, Matthew!
RAW file would perhaps be best for evaluation, Lightroom and Camera Raw should be able to handle the ZD format.
If you don't have a possibility to host a file via ftp or http, Pando service could be used -
www.pando.com. I haven't tried it yet, should work with Mac and Win and appears to be like e-mail where the attachment is uploaded to Pando's server for sharing. Maybe you could give it a try?