giving groupe rw permission to thunderbird files

[Linda]

Does anyone know how you can get thunderbird to give group rw 
permissions. I moved the profile to a  nfs and changed the permissions, 
but as soon as I access it, it changes files back to only user read 
write We have time share workers that I want to have use the same 
thunderbird profile but have different logins. I could make it run 
inside a script that fixes the permissions  after exit, but was hoping 
there was a way to fix this without doing that, especially since I was 
thinking about allowing access from winXP laptop so if they had to take 
care of mail when working at that station they would not have to 
physically move to an ubuntu computer and I have no idea how to make 
that work.

                                 Thanks
                                 Linda