It's a long time since I used Pluto, but my recollection is that
doesn't treat HTML attachments any differently to any other type of
attachment: You double click on it, a temporary copy is saved and that's
It doesn't parse the HTML in any way to see if any other attached
are needed by it, so they aren't saved alongside it - and therefore, as
you say, the images references aren't rewritten.
The bottom line, for users of Pluto, is that if you want to see
images displayed in the HTML, you'll need to save and manually edit.
(Remote images should be fine, of course).
Vince, I should be glad of further clarification. My understanding is that
MessengerPro doesn't behave significantly differently from Pluto when it
comes to handling HTML, but maybe I'm out of date because MessengerPro has
been subject to further development whereas Pluto hasn't. I see that you
use the former and should be interested to learn if that too is subject to
the same problems the affect Pluto, please. It may well be crunch time for
me entailing a reluctant swap to MessengerPro.