Christopher Larberg wrote: [verifiability]
One suggestion I have is to ask the copyright holder to create a PGP key set and sign the e-mail with his or her private key, as I and some others on this list do with all our e-mails.
While that is the ultimate solution I'm unconvinced how many copyright holders, in addition to doing us the favour of licensing their work under the GFDL, would be prepared to learn how to use gpg just so they could do it. We're asking *them* a favour and the onus is on us to make it easy for them, I think.
Cheers,
N.