In a template based application or a Rich Text editor, there is one point you always need to keep in mind when working with such tools; whenever you copy a content from somewhere to be pasted in this editor or any similar editor anywhere on the platform, please make sure you are putting only the Text version of it. What i mean to say, copy it from a word document, or from a webpage but before putting it in the Editor, use the NOTEPAD, paste the content there and then copy from the NOTEPAD and then put it in the template's editor.
The Reason:- whenever a piece of message/content is copied from a website/webpage/word document or any such rich editor, along with the message, it also copies the underlying code, and when the same is pasted in the editor here, those underlying codes also get pasted. You couldn't see them but they make the output look really weird. Hence, it is always advisable to paste a plain text content taken from the NOTEPAD and then apply the needed formatting.