We’ve just updated our spam recognition mechanism to include a variation on ‘grey-listing’.

As part of the content analysis we now check for common phrases present that would not typically be expected in normal email. If they are present and we’ve not seen them from the particular sender recently we temporarily reject the message. If the message is presented again after a short delay we will mark the email as spam allowing your particular rule (accept,reject,tag) to occur and delivery appropriately.  Since the vast majority of infected PCs acting as spam senders do not operate as proper email senders with industry accepted retry periods they do not send the same message again and so the spam no longer reaches your inbox.