Remove Unwanted <p>

Wrap them in empty div tags! When you're in the WYSIWYG, you can edit the HTML, and there when Marketo would normally throw in paragraph tags, you can instead wrap the content in <div> tags. Marketo considers these acceptable and therefore won't swap them out with <p> tags, and in emails your <div> tags (probably) don't have any actual styling to them, so it doesn't affect formatting in email clients.

The WYSIWYG replicates the HTML wrapping of the line you're currently on when you go to a new line. So if you edit the WYSIWYG HTML to be <div>Placeholder paragraph here.</div> and then swap to the non-HTML editor, you'll be editing the text wrapped in that div. When you hit Enter at the end of that line, it'll create a new line wrapped in the same HTML—you'll be creating more <div></div> lines.

You should be careful about using this if either you or your team doesn't understand HTML. Changing the way the WYSIWYG functions like this will quickly change the acronym's meaning from "What you see is what you get" to "What you see ISN'T what you get."

Cheers,
Edward Unthank | Founder, Etumos