Thank you for reaching out to the Constant Contact Community. I hope you are having a safe and happy weekend!
I'm sorry that you are encountering issues with invalid characters. Footers are perfectly acceptable and that shouldn't be causing the problem. Can you please send an email to social_support(at)constantcontact(dot)com with your username, a reference to this post, the name of the campaign, where you are trying to insert your content, and the content that is triggering the error? We are happy to take a look and find you some resolution.
Thank you for choosing Constant Contact. Have a great day!
Adrienne B. Community & Social Media Support
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