If you want to block emails from a specific address, follow these steps: (in your email window)
Hit the 'Gear' icon
Hit 'Advanced Settings'
Hit 'Filter Rules'
Hit 'Add New Rule'
Hit 'Add Condition' - Hit 'Sender/From'
In the 'Contains' box, add the EXACT address of the email sender that you want to block
Hit 'Add Action' (pick any action you choose; if you choose 'Move to folder', it will then ask you which folder, type in, Hit 'OK'
Hit 'Save' (you will then see the blocked address listed; if at any time you want to undo this action, just hit the trash can along side the item and the filter will be deleted.
There you have it !! It works!! Yea!!
There is one correction on the above process. No need to hit 'Advanced Settings'. Go straight to "Hit 'Filter Rules'. Also after "Hit 'Add New Rule', paste the EXACT address of the email sender that you want to block. (This will allow you to see the exact addresses in the list of filters)