Mobile Yahoo client not using alternate view, showing html code instead
We are sending HTML emails, with an alternate view (Content-Type: text/plain; charset=utf-8; Content-Transfer-Encoding: base64) for non-HTML clients.
The email mobile client shows only the HTML view, and does a partial download of the content, so the HTML is malformed (3 pages of garbled HTML code). If you click the "View full HTML message" button, you get the correct message, but we'd prefer the client to show the alternate view and present the option to download the HTML message.
Why isn't the alternate view being used?