If you wish to block someone who sent you an inquiry, follow this link to the Leads Received page. Find the inquiry they sent you and click on the row. This takes you to the detail page for the inquiry. Click on the Block button and the person is blocked from sending you inquiries.
If you wish to report someone who received an inquiry from you, follow this link to the Inquiries Sent page. Find the inquiry you sent and click on the row. This takes you to the detail page for the inquiry. Click on the Block button and the person is blocked from sending you inquiries.
You can only block people who have sent you an inquiry or received an inquiry from you.