I want to block the emails i see as spam so they no longer go to the inbox of the mail users. I'm the admin of a domain and i've asked the users to forward the spam emails to me, so i can start blocking them. I tried adding mails to the spamfilter blacklist but it did not solve the problems. Emails still go to the user's inbox with the subject modified with a '[SPAM]' tag. How can i block the spam and send a reply to sender announcing them they are identified as spam? Can i use some other spam databases or something to block spam?