I've been sending this email out to around 170 chefs for over a year now. I get between 35 - 40% open rate. I feel like I'm getting into a rut but it seems to be effective. I'm trying to get some out of the box opinions on it's readability and ease of use.
Thanks for posting your email! Your email open rates are great! Here are a few suggestions for you:
Try to match some of the colors of your website to your email. Right now the two main colors of your email are black and white. On your site, you have brighter colors like the main background color of yellow. If you pull in this color, or maybe some of the other blues or reds to make certain text stand out, it can help draw the eye to an individual section of your email.
You have a couple of pictures now, but you might be able to add more, for either the specific fish (i.e. Haddock or Halibut) or for your Categories (GroundFish, Scallops, etc.)
I would also recommend if possible, to try to use the same font and size for the bulk of your text. You could have a heading size (maybe 14 or 16pt) and then a size for the other text (maybe 10 or 12pt).
I hope this has helped. Let us know if you need any help matching colors to your site.