Hoping that Constant Contact enables a separate preview thumbnail setting in each email soon --  has beat you to providing this capability. Most organizations sending emails always lead with their logo as a default header image, thus always their "first picture", and unfortuntely, this translates into a very generic social media visual. I often create a work-around by duplicating my Constant Contact email, deleting the header logo, blasting it to an email list of one contact (me), and using the url generated through this jerry-rigged fake email as my destination for social media. Which is really unfortunate.  ... View more