Hmm, what is the difference between clicking a link and copy/pasting it? This is a little hard to investigate because links in email messages usually open in a new tab, so the normal Network Monitor loses track of the request and it's tricky to see the exact difference between the clicked link and the pasted link. You could try using the Browser Console (Ctrl+Shift+J). Change to Multiprocess, click the gear/wheel button and turn on Enable Network Monitoring, click the Requests filter to turn it on, then finally click the trash can. Now keep this open while you launch the link from the email and compare with what you expected. Does it look like some security service or add-on (or beta feature?) is removing the key because it looks like a tracking parameter?