Rolf,
You can copy-paste from those applications, but you have to be careful.
The problem is that some applications like Word include more than just text in their paragraphs, they include all sort of formatting and control characters, as well as special features, that you will also end up copying into PrintShop Mail. PrintShop Mail, however, might not know what to do with these, so it could produce unexpected behaviors, formatting issues, etc...
I'm not sure about the other softwares, perhaps it would work better with them. But the general rule is that you can copy-paste the text, but the formatting will probably be lost in the process.
Regards,
Raphaël Lalonde Lefebvre