It seems that when a Tweet is included in a post, the email that goes out to subscribers is a multi-part HTML that is not rendering. Viewers only see code:
Content-Type: text/plain; charset=UTF-8; format=fixed
And so on. The Tweets are not included. The post in question is at
I see there's a setting to "include tweets in the digests." Do you consider messages of individual posts to be "digests"?
Also, the documentation talks about "View a live preview of emails before sending," but I can't find where you would do that.