Black List Sender Email Addresses (protogenist.wordpress.com)

This is a simple spam blocking technique that is often used. Users create a black list of from addresses that should be prevented from entering the network and reaching the user’s inbox.

There are a few disadvantages with using this technique. Because spammers can create many false from email addresses, it is difficult to maintain a black list that is always updated with the correct emails to block. Also, some spammers do not even use a from address so a black list would not be able to catch these cases