There are multiple reasons for one to block certain incoming mails, such as email advertisers, spammers (if Gmail doesn’t catch them), insistent online shops or websites that refuse to unsubscribe you or stalkers, being ex-girlfriend/boyfriend or anybody else. Fortunatelly, Gmail allows us to create various filters and we can block any email easily.
As shown in the attached image, all you need to do is check the email which sender you need to block, click on the more action rolling menu and choose “Filter messeges like this”. You will be presented with another window and you can notice that the sender was automatically added by Gmail. Press “Next step” and Gmail will let you choose what actions you want applied to the filter, such as deleting the filtered email when it arrives or forward it to another address.