We say the email is private data, so reasonably we shouldn't reveal it
indirectly through a hash sum: http://xmlns.com/foaf/spec/#term_mbox_sha1sum

Also, the unselect rule for DELETE was useless anyway since it would
already have been filtered out by not having true.

(the => false stuff are for when you want ALL _except_ that)

Not that I think we could break out of the directory since
we use basename, but you never know... maybe there's a unicode
bug in PHP or something.