Word can add a lot of extra HTML code when you copy text and Firefox can display this as spaces. If Word allows to copy (place) plain text to the clipboard then try that. Otherwise you may have to first paste the text in a plain text editor to remove the extra code before pasting in the email.

• https://developer.mozilla.org/en/Tools/Scratchpad

Would I have to do this every time I want to copy and paste?

Only in applications/programs that you have a issue with.

People try to make web pages using Word and the code is terrible.

Can just use plain text rather than HTML if just doing Word stuff.

If you copy Word text in rich text editor window then you can expect issues, especially if you have edited the text in Word as that can open and close tags or produce nested tags. You can inspect page source to see what Word makes of it.