Can't Access Constant Contact Links

Information email messages from both my doctor and and my homeowners association frequently contain links to the Constant Contact website https://r20.rs6.net. If I click those links from either eM Client or from the Gmail web page, I get a “can’t connect to server” error in Firefox, Chrome and Edge. Who or what is causing those links to be blocked, and what do I need to do to unblock and reach those links? I have Malwarebytes and Webroot security running.

Information email messages from both my doctor and and my homeowners association frequently contain links to the Constant Contact website.

If you are receiving these emails only from these two senders and no one else, then those two computers have some sort of (as you say) Malware or Spyware or something similar that has hijacked their mail clients and sending those links in their outgoing mail that you then receive.

I would contact these two peeps directly and let them know to have their computers scanned.