Comment 18 for bug 192629

You can also specify these options for an external USB drive or partition: Open Places / Computer and select Properties for the partition (volume) in question. Then on the Drive or Volume tab you can specify the options you want in the Mount Options text box, eg "umask=000,uid=1000". Once you unmount and remount the partition, trash starts working correctly.

I still think these should be the default mount options for external NTFS drives. After all, that's how windoze treats them, and consequently nobody expects an NTFS drive to be secure.