Thank you for reaching out in the Community. I'm sorry to hear the campaign is not displaying as it should for some of your recipients. Based solely on what you're saying without any testing my initial impression is some of the recipients might have their screen resolution set to a higher DPI and the e-mail will display larger as a result. Of course, we would love to investigate this for you.
If you do not feel comfortable giving this information publicly, please reach out to us at social_support(at)constantcontact(dot)com with the name of the campaign in question and if possible, what e-mail clients (Gmail, Yahoo, Outlook, etc.) they might be viewing it in.