We need to clean up the output from "Subscribe By Email"

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:

--67218549252d2dd2f89e7b9.78959070
Content-Type: text/plain; charset=UTF-8; format=fixed
Content-Transfer-Encoding: 8bit

And so on. The Tweets are not included. The post in question is at

http://blogs.shu.edu/hylandmi/2014/01/12/tweets-you-may-have-missed-last-week/

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.

Thanks!