Just a workaround for now.
Create a symlink from mounted network share (samba or other) to a local folder
e.g. sudo ln -s /home/username/.gvfs/srv_folder\ su\ 172.16.0.1/ /media/srv1
Now create a bookmark to /media/srv1
Accessing this bookmarked folder with thunderbird work greatly: all file are attached correctly.
Note: if you unmount network share, symlink is broken, so folder is not accesible. When you boot machine is necessary to mount all your desidered network share.
Just a workaround for now. .gvfs/srv_ folder\ su\ 172.16.0.1/ /media/srv1
Create a symlink from mounted network share (samba or other) to a local folder
e.g. sudo ln -s /home/username/
Now create a bookmark to /media/srv1
Accessing this bookmarked folder with thunderbird work greatly: all file are attached correctly.
Note: if you unmount network share, symlink is broken, so folder is not accesible. When you boot machine is necessary to mount all your desidered network share.