Sales Insight - exclude/strip tags on paste

We have a Marketo email made available to sales reps in Salesforce, using Sales insight. 

When a user copies a block of content from a separate email (bulleted list with links) then pastes it into the Sales Insight email, formatting can often get pretty chewed up. Which is understandable, but also a pain to fix because the Sales Insight text editor just doesn't make it easy to fix. 

So, my question: Is there a way to strip or prevent the code getting placed into the template? I could ask the sales rep to copy to a text editor and paste from there - but... it's a sales rep. We're adding steps they won't like, and maybe wouldn't do. Then they get frustrated with the Sales Insight tool and don't use it.