> Can someone tell me what this error message means, and whether it is a
> permanent error?
>
> >  --- The transcript of the session follows ---
> >bellmail: cannot append to /usr/spool/mail/ozmen
> >bellmail: cannot create /root/dead.letter
> >bellmail: error closing file: A file descriptor does not refer to an open
> >file.
> >550 <[log in to unmask]>... Insufficient permission

It's a problem with the other system.  It will probably persist
until the system administrator there fixes the problem.