Comment 19 for bug 316272

> From header validity isn't assured by DKIM. What other basis for
> this assurance do you have?

That's seems like enough to scupper this plan.

To try and understand something about DKIM I've been reading the
Wikipedia article: http://en.wikipedia.org/wiki/DKIM

In there, when talking about the DKIM-Signature header, an h tag is
mentioned, which lists the headers that are signed. From what I can
tell, Google includes the From: header in the DKIM signatures they
compose.