If I release a video and send an email newsletter at the same time, which one caused the traffic increase? Should I invest in making more videos of sending more emails?
If you insist on knowing, include a different url in both that goes to the same place and use your damn server logs. You don’t need google analytics and whatever.
presumably you control the urls you are sending in the email. As a result if you want to use query strings that's fine. The issue only arises when you use query strings to implement tracking on someone else's site instead.