bug#38169: Idea: custom From names ("From Personalities")

["積丹尼 Dan Jacobson" <jidanni@jidanni.org>]

Just the other day I was reading (info "(message) Reply") and I suddenly
had a new idea: "From personalities". [Feature request].

Let's say we are replying to mom@nurdfamily.org.
Well, we want our From: headers to say
From: James Fartdom <james@example.com>,
or even
From: Your loving son James <james@example.com>.

But let's instead say we are replying to secretary@plaztziph.com.
Well in that case we want our From: header to look like
From: Chairman Fartdom <james@example.com>,
or even
From: Chairman J. Fartdom <chair@plaztziph.com>.
or even
From: Military Purchasing Director <mpdir@mil.mil>.

Well all this could be accomplished with an alist of patterns of who we
are replying to, vs. what header we should use, and what is the default
if no matches.

Note: what if it is a wide reply, and we are replying to both your mom,
and the CEO? So maybe ask the user what From to use.

Also note, this all will work great when *replying* to a message,
but how about when composing a *new* message?

OK when composing a new message, first insert the default From:,
and then when the user finally pushes the Send button, ask the user
''Mom detected. Use "Your loving son" From? [y, n, ?]''
and then give the user one final look to see if he is happy,
and then send the message.

(Users should note that their ISP might reject sending using any other
domain than the one they are paying for. However at least using Your
loving son instead of James Fartdom should never run aground.)