Internally at my company we always do scream tests as part of our EOL process because we know we can't reach everyone, even our own employees.
https://www.microsoft.com/insidetrack/blog/microsoft-uses-a-...
Fun story: my mortgage got sold last year. Not the first time. I got emails from the old mortgage company and the new mortgage company about the sale, but I skimmed them. I got letters via USPS from the old and new mortgage companies, but I mostly ignored those because 95% of what mortgage companies send me via USPS is junk. So I missed the fact that my automatic payments didn't transfer over. The new mortgage company let me get four months in arrears before they finally FedEx'd me something overnight. That got my attention. I was like: you guys should've FedEx'd me this in the first place. For all they knew, I wasn't getting their emails or letters in the first place because nothing had been sent signature required.