I just did this, but haven't tried to replicate it (for obvious reasons). I mounted a shared volume, and sent an email with a file on that volume as an attachment. I then unmounted the volume and turned off that computer
Now if I go to my "Out Tray" and click on that email with the attachment, PowerMail goes off with a rainbow pizza cursor for ever. Worse, it takes _two_ force quits to get PowerMail to quit, and then after it quits it cannot be re-launched without restarting my Mac. (Finder Error -800, Unable to complete that operation). Augghhh!!! (to quote Charlie Brown). Powermail is pulling away the football a little too often for my comfort level. A

