> Do serious companies not have canaries or other checks in place to ensure their notifications are correctly delivered to customers? Even with a canary, you h

> Do serious companies not have canaries or other checks in place to ensure their notifications are correctly delivered to customers? Even with a canary, you have no guarantee that a particular customer will receive your email. In this case, maximum CYA is a certified letter sent return receipt requested. There are services out there to mass mail those.