Created attachment 109105 [details]
Suggested path

Ultimately my goal is for KMail to display the attachment icon next to emails that have attachments. I have narrowed down the issue of emails with attachments for which KMail does not display that icon to multipart/alternative emails in which the attachment is in the HTML part. Before revision 83859810 of KMime, the code had a flag to detect attachments even inside alternative parts, but that does not seem to be the case and it explicitly ignores alternative parts now, which is wrong for some (many?) use cases, including Akonadi flagging an item as HasAttachment (which is what ultimately is used to show the KMail icon) because the email in fact has an attachment in one of its forms.

I could patch the code but I am not sure about the implications elsewhere or what the desired behavior is (assuming the current behavior is not the desired one). For instance, the attached patch descends into the parts of a multipart/alternative email to check for attachments, but attachment-looking parts that are immediately under the multipart/alternative container are not considered attachments. This does not break the tests according to ctest (but the patch does not add a specific test like having a multipart/alternative composed of a text/plain and an image/jpeg).