I'm pulling out some of my last remaining hair with this problem. When clicking on a Reddit post email link in Apple Mail Safari gives the error: ... "Safari can't connect to the server 'click.redditmail.com''. Firefox gives the error "Firefox can't connect to the server at click.redditmail.com".
If I paste the link into Chrome it does bring up the post. Sometimes Safari will bring it up as well but after a while it will error out again.
I have disabled Control D, Little Snitch but the problem persists.
Hoping someone has some suggestions as to where to look. Maybe some Firewalla Gold Pro configuration issue?