Gmail comes with a useful option of creating filters that can automatically block emails based on sender’s email address or from an entire domain.
To block emails coming from a specific domain or even a specific email address, first create a filter for that.
To do this, click on the down arrow next to Gmail search box at the top.
Then, in the From field, fill out the sender’s domain or sender’s email which needs to be blocked. Click on Create filter with this search at the bottom.
The next step is to determine the automatic actions that Gmail will perform on messages originating from that specific domain or email. Since, in this case, we need to block, it is best to delete these messages as soon as they arrive. So select Delete it.
To delete earlier messages from the same sender, select Also apply filter to matching conversations.
Finally, choose Update filter for this blocking filter to become active.
At any time, this filter can be modified or deleted. This can be done by accessing the gear icon at top right of Gmail and selecting Settings > Filters.
In a nutshell, all this filter does is automatically move messages that are from a specific domain or email address directly to Trash folder (where they will be deleted automatically after 30 days) without ever landing in the Inbox.
This is a great way to tackle spam, improve productivity and to completely block messages.