I’ve heard this “active number” and “active email” thing for a while, but isn’t the fact that the message wasn’t “returned” undeliverable a sign already? If I s

I’ve heard this “active number” and “active email” thing for a while, but isn’t the fact that the message wasn’t “returned” undeliverable a sign already? If I send an email to a GMail account that doesn’t exist, Google will reply that the account doesn’t exist. It’s the same with calling (every carrier) and texting (at least with AT&T; I just tested it)