Spammers are too clever to use the same email address and so they clone addresses often hijacking valid ones. This means that attempts in OE to block a particular address are unlikely to stop the flow of spam into your mailbox.
Similarly you could try blocking based on certain words but this requires an extensive amount of work to set up. There are a number of Spamkillers around that will help by identifying the spam but if you want to stop it entering your OE account in-box then the best option is to consider using something like MailWasher. click here