Comment 2 for bug 105088

This happens to any version of Thunderbird (1.5.0.10 and 2.0.0.4)

To verify map a SMB drive in Nautilus. Open Office can access the data on the share. Thunderbird cannot access data (like adding or saving attachments).

This is due to the fact that gnome_vfs requires a different approach to storing data on virtual drives.

By far the best solution would be to require Gnome to access virtual drives like local ones. In order to achieve this, a redirection within Gnome would be required.