Zip folder contents missing

Hi all,
XP machine with Outlook 2003. I’m sending a zip file with empty folders in it all named different things. I send it to someone and he says that the contents are missing.

I made sure that the spam/virus filter is not stripping the attachment. Then again the zip file itself is received, but not the contents. This seems weird as a filter usually strips the zip file itself. the person is on another domain.Sending it to someone on the same domain is successful (can see contents).

Anyhow, what would cause the contents to be missing? Permissions seem ok.