Why does the newsletter opt in form on my Wordpress site look strange?

There is an issue with wordpress in which the formatting of newsletter opt in forms are lost when you go back to visual mode after pasting in the opt in form code. This happens regardless of what wordpress theme and/or autoresponder service you use.

The trick to retain the formatting is to add the newsletter opt in form code last. This means that you need to do everything else that you need to do on your wordpress page or post, then go to HTML mode edit view to paste in your opt in form code. And do not go back to visual mode edit view after pasting in the code as doing so will cause the form to lose its formatting.