Kmail 5.3.0, html emails with PDF att-achments

Hi
I'm having an issue with a HTML email I received with a PDF att-ached, if I 
try to reply to it, it opens the composer with the original message and loads 
of unreadable text (I assume its a binary dump of the PDF). (I received this 
email in the previous version of milkmaid).
If the originating email is not html, it works fine. I unfortunately can't 
find any other html emails with a PDF att-ached to make sure it happens all 
the time.
Anybody else seen this ?

Regards

Ian

(i had to spell "a t t a c h" badly to ignore the message pointing out i've 
not added anything to the email because the "Send As is" doesn't seem to work 
either)
-- 
Qt: 5.6.1
KDE Frameworks: 5.25.0
kf5-config: 1.0
KDE Plasma: 5.7.4
Kernel: 4.7.2-1-default
opensuse:tumbleweed:20160828