I think it’s appropriate for a service that allows you to permanently block senders, to make those senders know they couldn’t reach you. It’s just like if someo

I think it’s appropriate for a service that allows you to permanently block senders, to make those senders know they couldn’t reach you. It’s just like if someone calls you and you never answer the phone, they leave you a message. They assume you got the message. But in this case, you don’t. I think there are some things for what you’d like to be notified if someone could not receive your email.