Open Gmail
Open the email from the sender you want to block
Click More (three dots) next to the email
Click Block [sender]
Confirm by clicking Block
Open Gmail
Click the search bar dropdown (sliders icon) or use the search bar with: from:example@domain.com
Click Create filter
Select the option to Delete it (or Skip the Inbox)
Check Also apply filter to matching conversations
Click Create filter
Open Gmail
Click Settings (gear icon)
Click See all settings
Click Filters and Blocked Addresses
Under Blocked addresses, add the sender or domain in the “Add a new filter” field
Click Block
Click Save changes