To me, what makes an email great is that the content of the email is relevant and timely. The daily-ish email is THE best sample of great content that is relevant.
Cassie - your passion for the topics really come through in your writing of the daily-ish emails. Your unique bubbly voice also comes through consistently. Few people possess the discipline and enthusiasm to make the daily-ish email happen. You should be proud of your work and and know I, and many others who have posted (or not) in this thread, appreciate your hard work. You are essentially giving all the subscribers multiple spoons every day, which is a beautiful gift to us all
I think it may be tempting to spend time/resources on making the email prettier, but please be careful not to compromise on the content, which is the star of the effort. I personally like that the email is text only, and my research would suggest that the majority of the subscribers check their email on mobile devices, and text is likely the only approach that will work consistently well on any device, as well as not costing much bandwidth to those with limited bandwidth (like me).
Just to give context - I work for a large brand and personally send out more than 100 emails per year as part of my job, so I am subscribed to tons of the best emails out there in a bunch of different industries.
Thanks again and please keep on the great work!
p.s. - Paul does a great job too!