Unfortunately, "blocking" emails by address is all but useless unless the sender is a person without the technical savvy to subvert it. Those that send spam, phishing, and other undesirable emails continually adjust their tactics and are quite good at either faking (spoofing) the From address or simply using a new address every time.
If the unwanted emails are from a legitimate company then you may find that unsubscribing from their mailings, and/or blocking is effective. However, for spam, phishing, and other aggressive email, the only effective way to combat them is on the server, before that mail reaches your Mail Inbox. This therefore requires both making appropriate settings on your account (i.e. iCloud, Google, Microsoft, etc.), as well as always, and repeatedly, marking spam messages as Spam/Junk. When large numbers of users mark similar emails as spam/junk/phishing, the server's training algorithms begin to recognize and automatically block such messages.
To effectively cope with undesirable email, you should be repeatedly using the tools available to you to Reduce junk mail in Mail on Mac - Apple Support. On iPhone "Move to Junk" is an option available on the message options menu at the bottom while viewing a message.