If I am not mistaken, when dealing with multi-part messages, currently DeltaChat displays text/plain by default, and hides text/html under the “Show full Message…” button.
text/calendar and other mimetypes are currently not displayed anywhere, right? Would it be possible to either have a dropdown in the “Show full Message” screen that lets you select the mimetype for the content to be displayed?
I suggest you try it with a real message and see what happens. Most likely unknown MIME type will appear as a separate message bubble with an attachment or a “file” attachment that you can download.
This thread was indeed prompted by a few mutiparts messages I was recently sent by non-delta-chat users. Text/calendar is visible in normal email clients, but ignored by DeltaChat.
I can upload the EML or something if this is not the intended behaviour.
It’s not indended behavior, attachments should not disappear.
If you can send it to me in PM (click on my avatar) or as an attachment to office@merlinux.eu, I can turn it into a test case.