Function deltachat::mimeparser::get_mime_type

fn get_mime_type(
    mail: &ParsedMail<'_>,
    filename: &Option<String>,
) -> Result<(Mime, Viewtype)>

Returns the mimetype and viewtype for a parsed mail.

This only looks at the metadata, not at the content; the viewtype may later be corrected in do_add_single_file_part().