Robert Bihlmeyer <e9426626@stud4.tuwien.ac.at> writes:

> per default, inline parts have no visual separation from other inline
> parts.  This is arguably correct for normal parts, but very wrong for
> message/rfc822, at least.

> The only indication that an inlined (forwarded) message/rfc822 starts
> is the sudden appearance of mail headers.

I'm all for the principle than underline should mean clickable, more or less.
I render _underline_ with a yellow background ("seashell1", to be precise),
to simulate what we call a `crayon à souligner' in French (I think English
people say "underlining pen" or "highlighting pen").  Plain bold should not
be abused when avoidable, and I prefer to use background colouring instead.

> this is a demonstration.

These principles are fruitful for cases like in-lined message/rfc822.  I'm
including a picture of your demonstration, below.  For me, it is absolutely
clear that I'm looking at a quoted message.

> There is no indication of the message's end, whatsoever.

Here, you have a point.  I do see a plain:

   (this is the last line of the inner message)
   (we're in the outer message, again)

on my screen.  When the message has signature, which is the usual case,
such problems do not exist, as Gnus uses a pretty characteristic rendering
for signatures.

Maybe that Gnus could invent a mere `-- ' (rendered as a signature) when
rendering a message/rfc822 in a MIME part, which has no recognised signature?

Here is the promised picture: