Back in 2016, we made enhancements so that our system does handles most non-ascii characters. This solved a lot of issues with pasting from MS Word.
However, it is still not recommended to paste from MS Word and this is particularly true with email broadcast.
There are two issues. The first issue is that databases and some email readers just can't handle the unique characters that come from MS Word. So what you might have created as a simple dash (-) in MS Word is unrecognizable to some databases and some email readers. We've added functionality to handle that in our own database system and Email module but obviously don't control the email readers out there. The second issue is that you're carrying over the formatting so you're not just pasting in the text but also the font size, color, line-spacing, etc. This might be what you're wanting but it overwrites the default formatting in the email template and might not display as well as you'd like in the email readers.
What to do. Our recommendation has always been to carry over just the text. Go ahead and write your email body in whatever text editor you prefer (almost always MS Word) but before you paste into your email, take one additional step of copying and pasting in an ASCI text program.
for MSFT users, that's Notepad. Just open Notepad, paste your text, then rec-copy it and paste into your Blue Utopia email.
for Mac users, paste into TextEdit but since TextEdit can handle special characters and formatting, you do need to take the additional step of saving as text only. Then copy and paste into your Blue Utopia email.
What this does is it copies over just the words, without formatting and without illegal characters. Now, you can format with the integrated html-editor.