Links in emails aren't forwarded properly

We've had a problem recently where some but not all users are reporting that the links in our emails don't work. They are hitting a "can't reach this page" error on the cc.rs6.net forwarding URL. Its working fine for me, but I have multiple users on different networks reporting the problem. I tried troubleshooting and was just told this was a known issue and that recipients can whitelist Constant Contact in their security settings, which feels pretty hopeless as a solution for all recipients. Is there any timeframe for a solution?