Blocking mail from certain senders
Sometimes you may get unwanted mail that isn't necessarily spam.
While you can't currently block messages from specific addresses or domains, you can set up a filter to send those unwanted messages directly to Trash.
To set up a filter, follow these steps:
Click Create a filter under the search box at the top of any Gmail page.
Fill in the appropriate fields with the filter's criteria, and click Next Step.
Choose the action you'd like for these messages by checking the appropriate box. (In this case, we suggest checking Delete it.)
Click Create Filter.
Blocking mail from certain senders - Gmail Help