Blocked emails still coming through that still have the blocked symbol on them.

I just received another junk email that I previously blocked. I wasn’t sent from a different address because it still has the read blocked symbol on it from when I originally blocked it. This happens quite frequently and I don’t know why. I’m quite familiar with the same junk emails being sent from different addresses because I receive many of them in the same day. When I block them, I can see that they’re different addresses. And it’s never ending. But I don’t understand why the ones with the blocked symbol on them are still coming through. They come right through with the symbol still on them and I just got another one today. Also, when I block an email, it doesn’t always put the symbol up. It still shows the email blocked, but no symbol. Just curious as to why it puts the symbol up on some blocked emails and not others.