Spamers rarely use the same address twice, so blocking them doesn't usually achieve much but I do it anyway. Blocking doesn't actually do anything more than clear messages from that particular address from the mail server without downloading them to your PC. It doesn't send any message to the spammer.
If you want something a little more effective, try one of these click here
If it gets really bad you may find it better to set up a new mail address, but how long it'd stay clean is anybodies guess.