To have Gmail send messages from a specific sender to the Trash automatically using a filter you set up and maintain:
›› Step by Step Screenshot Walkthrough
Click the Show search options triangle (▾) in the Gmail search field.
Type the desired email address under From:.
You can block an entire domain by entering just that. To block all mail from both firstname.lastname@example.org and email@example.com, type “@example.com”.
Tip: To block more than one address, separate them with “|” (the vertical bar; typically above the backslash on the keyboard; not including the quotation marks). You can block both firstname.lastname@example.org and email@example.com by typing “firstname.lastname@example.orgemail@example.com”, for example.
Click Create filter with this search ».
Make sure Delete it is checked under When a message arrives that matches this search:.
Click Create filter.
Tip: Check Also apply filter to [__] matching conversations to delete previously received messages.
To archive and label instead of delete messages, choose Skip the Inbox (Archive it) and Apply the label: under Choose action when setting up the filter.
Of course, you can always unblock somebody you have blocked using a filter in Gmail – or whitelist an address altogether from being put into spam.