Using demo SysTools DBX COnverter (from *.dbx to *.pst) I converted the mails. In eM Client I imported these mails but none of them contains any attachment even if the conversion seems to be succesfull (nearly the same size).
Have you tried importing directly from Outlook Express? It is an option in eM Client.
Unfortunatelly I don’t have Outlook Express on disposal… That’s why I had to use that demo programme.