Blocked contacts aren't effectively blocked!
why do blocked contacts continue to be able to leave messages and send emails? Latest iOS on all devices.
MacBook Pro 13″, macOS 15.6
Blocked calls are simply rejected by the phone, which means they are shunted off to your carriers voicemail system.
In order to block them from leaving voicemail, they would have to be blocked at the carrier level, not the phone.
Contact your carrier.
Blocking email senders is a separate thing from blocking calls or text messages.