For several years, I would send out emails using Constant Contact, but your templates and formats are limiting. You need to add a page-turning ability, and allow clients to create email campaigns that look like real magazines. I now use issuu.com for this (since Nov., 2012). My CC email is just a link to the eMagazine. You are large enough to incorporate this kind of design into what you offer clients. Click on the red link HERE in my monthly emails to see what I'm talking about.