> What it says is the list should re-sign if it modifies the message
> (or, in general, re-sign anyway). So append whatever you want,
> just re-sign the message. Are you insisting that advice is
> defective?
Defective, maybe not.
But I don't think I would follow it for my own lists. I'd rather
remove the signature and tell people who are using anal-retentive ISPs
that refuse to pass unsigned messages to switch, because there are too
many people out there who will report you as a spammer rather than
unsubscribe. I don't want my signature associated with any such
thing.