Hmmm. I thought I had something in Firefox (setting or addon) that didn't send referrers for external sites when you click-opened a link in a new tab. But it doesn't seem like it anymore.

There are a number of settings for this: https://wiki.mozilla.org/Security/Referrer

Thanks. Do you know if some of these break major websites if I move away from the default settings?

I've had a small number of sites break when not sending any referer. Can't remember any concrete examples off the top of my head though.