Yeah, its starting to get weird that they refuse to implement this. Its almost like certain stakeholders need to be able to randomly text you with malware and refuse the notion of being silenced.

Same thing with the iCloud email addresses you can't delete and that have to exist if you have an AppleID, despite never using them.

There is a "Filter Unknown Senders" feature.

https://support.apple.com/en-au/guide/iphone/iph203ab0be4/io...

Notably this doesn't actually prevent a zero-click exploit from being received.

Is this needed on top of lockdown mode?

I don't want the huge number of inconveniences of lockdown mode. I just want to have apple block messages from unknown senders to iMessage server-side, before they forward any untrusted data to any of my devices.

lockdown mode also doesn't add server-side filtering for unknown imessage senders, so that doesn't seem as good for this purpose.