i tried to reproduce what you are getting, but if i add a header or footer and type an email address in the header or footer, it leaves it as regular text without the hyperlink to email someone. Are you wanting to keep the hyperlink so it can be clicked and an email client opens or are you wanting the email address with no formatting?
maybe try having a field within the form with the email you want and add that to the header or footer, and do your formatting within that text box.