Spam in Apple mail

Many spammers are using different variations of the same email address. For example:

1. 12345@domain.com
2. 123456@domain.com
3. and so on

So, even though you may move one email address to Junk, the other variations also have to be moved individually. Or you can use the Edit/Select/Move process.

I can’t answer for how any other servers handle spam.

Probably you mean iCloud Mail.

To make sure future messages from the same sender are marked as junk, you can report messages as junk in the Mail app. On your iPhone, iPad, or iPod touch, swipe left on the message, tap More, then tap Move to Junk. On your Mac, select the message and click the Junk button in the Mail toolbar.

Report and block spam in iCloud mail - Apple Support