Dekko does not show attachments with 'Content-disposition:inline'
MIME message parts with content-disposition:inline should be displayed as part of the mail if possible (e.g. embedded images). If the file type cannot be rendered, most mail software resorts to handle it like an attachment, so that the user can download and save it. Dekko does not do that, it silently ignores embedded parts it cannot render. (I noticed when I received mails referring to an attachment an could not find it in Dekko. Opening the same Email in other software showed it as a normal attachment.)
Dekko should not silently ignore message parts with content-disposition:inline. It should handle them like attachments.