Are Gartner Digital Communications Legit?

I am getting an increasing amount of spam/junk email. It covers such things as Credit Cards, PPI, Casino etc but the email address of the senders is the subject, and there is no subject title included. When I click on the senders email address I see really strange addresses. I block all of these mails but it is no good as more still arrive with the same email address ie PPI Refunds but a very different domain. The filter to set up a rule requires an  email address which I cannot give, and there is nothing in the incoming mails in the subject box, so filtering by word(s) is not possible. The emails don't contain attachments. What is required is a filter to search the message itself.