It's also worth bearing in mind that some ISPs and e-mail providers have their own spam/junk filters. That's quite apart from whatever spam filters an end-user has installed on their own PC. I know, for example, that BT Internet operate such a filter. Consequently, it's necessary to log into BT Internet from time to time (ideally every few days) just to see what has been prevented from being sent to the intended recipient. It's quite surprising what gets removed like this. If in doubt, check it out!