Some spam probably does this, some probably does not. As mentioned, tracker pixels can also confirm, but either way if the message was delivered to your inbox with no bounceback, even without opening it the sender can infer it is active.
That said, a “legit” company domain like StubHub should be safe to click on (as long as you are careful it’s not a spoofed domain) and unsubscribe.
Some spam probably does this, some probably does not. As mentioned, tracker pixels can also confirm, but either way if the message was delivered to your inbox with no bounceback, even without opening it the sender can infer it is active.
That said, a “legit” company domain like StubHub should be safe to click on (as long as you are careful it’s not a spoofed domain) and unsubscribe.
Good email clients block external images by default.
Great email clients let you view external images but block trackers. FairEmail does this for example.