I have done more research, and it seems that I can create the HTML for the newsletter in WordPress following the template they already had made. I would use the PHP API to create and send the email using their key to their email list on Constant Contact. I believe the API calls it a marketing campaign and the API would allow me to set parameters to choose an existing email list and use template codes for personalizing the content. Is this correct?   Anyone have experience with this to provide an estimate how long it should take for a plugin developer? ... View more