Mehssages

Do not go gentle into that spam SMS.

Filter SMS and MMS from unknown senders into a separate, muted list. SMS filter extension turns off notifications for SMS and MMS from people who are not in your Contacts.
Allowlist messages by sender phone number or body text.
Use iMessage app to add an item to the Allowlist or paste a phone number from clipboard.

NOTES:
* Messages for Apple Watch ignores SMS filter.