Currently in CRM v9 you cannot send a Quick Campaign with an email body larger than 50KB. When you do this it does not come back with any error, it simply ignores your request. You can use email templates with text larger than 50KB in the email body but you cannot without email templates. My idea is to support more than 50KB in the email body for Quick Campaigns when not using email templates. This is a product design limitation that does not appear to be documented. REF: MS ticket 118092219066630