CK editor messes up email HTML

I have some pre-formatted emails that I’m trying to send. All is fine as long as I just use the HTML editor. But sometimes that’s a bit cumbersome. The CK editor unfortunately seems to do whatever it pleases, such as removing and reshuffling some tags, especially <tr> and <td> tags, which results in messed up HTML…

Yes, I know it’s not a unique “feature” of this particular editor - plenty of others also have this issue. But regardless, it’s annoying.