Enable responsively designed emails.
Emails are being opened to a large extent on mobile phones with screens as small as 2.25" across and need to be readable at this scale. The top ESPs allow for responsive design.
Thanks for the feedback. Our design teams are currently working to provide responsive templates. We will update you when we have scheduled this into a release.
Mark Sorak commented
Actually, my marketing service just created a responsively designed an email template for me which I can paste into the html box in CC and it works just fine.