SUMMARY
Attached images in emails from applemail don't always show up - neither as inline images nor as attachments. The example email structure below is also initially shown as plain text. When toggling folder->message default format -> "prefer html to plaint text" to plain text and then back, the attached image and html payload is shown.


STEPS TO REPRODUCE
1. Receive email from applemail with attached image.
2. Navigate to that email.

OBSERVED RESULT
The text/plain option is shown regardless of the preference for HTML. The attachment is not shown nor indicated.
Navigating to another email and back again resets to the view to just showing the text/plain part (and no attachment).
The attachment is not indicated in the message list with a paper clip either.


EXPECTED RESULT
text/html potion should be shown. Attached image should be shown inline or as attachment.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: OpenSuse 15.2
(available in About System)
KDE Plasma Version: 5.18.6
KDE Frameworks Version: 5.71.0
Qt Version: 5.12.7

ADDITIONAL INFORMATION
I think the tricky bit is that the text/html portion is wrapped in a multipart/related section

Example message structure in apple-email:

Content-Type: multipart/alternative;
	boundary="Apple-Mail=_94C83921-FCDD-4332-8B84-399EFA3F5914"
Mime-Version: 1.0 (Mac OS X Mail 15.0 \(3693.40.0.1.81\))

--Apple-Mail=_94C83921-FCDD-4332-8B84-399EFA3F5914
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=utf-8

--Apple-Mail=_94C83921-FCDD-4332-8B84-399EFA3F5914
Content-Type: multipart/related;
	type="text/html";
	boundary="Apple-Mail=_B39D790E-FEC1-4CB1-B569-0E6E803B8B60"

--Apple-Mail=_B39D790E-FEC1-4CB1-B569-0E6E803B8B60
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html;
	charset=utf-8

--Apple-Mail=_B39D790E-FEC1-4CB1-B569-0E6E803B8B60
Content-Transfer-Encoding: base64
Content-Disposition: inline;
	filename="Screen Shot 2022-01-12 at 12.34.46 PM.png"
Content-Type: image/png;
	name="Screen Shot 2022-01-12 at 12.34.46 PM.png"
Content-Id: <25DB95B9-09D0-45A2-91DD-998FE82401FB>

--Apple-Mail=_B39D790E-FEC1-4CB1-B569-0E6E803B8B60--

--Apple-Mail=_94C83921-FCDD-4332-8B84-399EFA3F5914--