Navision F 2.6 and notes r5

I am using a combination of navision financials 2.60 and lotus notes r5 but the integration is not perfect. I’ve read loads of topics here on problems with using another mail client than outlook. But my problem is that when i try to send a report or something similar notes give the .html a funny extension like .n93 or something else. I can view the file with my browser but it is not practical for the “normal” user to have to choose a program to view the file. How can i get notes to name the extension correctly? I am hoping for an easy solution if possible [:)]