spam phishing and blocked addresses

going a bit goofy here over all the junk in my mail.  two problems really buggin' me

1. i have been faithfully marking emails to be blocked or blacklisted, but it seems that about half of the time i get a message the address is already on the list; why does blacklisting not block those addresses on my account?

2. Now i get a message that the blacklist is full and that i need to remove some items in order to add the latest offending addresses.  I cannot find the list or how to remove... can someone point out how to do that annnnnnd i hope that the list is time ordered 

thanks in advance for any help!!