Fraudsters these days now even set up sham law firms and other professional advisers. These firms can have websites and bank accounts, but they are still a front for fraud. So, for all payees not already known to you or your client, you must check them out. Law firms, accountants and estate agents are the most common and are all regulated, foreign firms are usually regulated too and you can Google who the relevant regulator is. You should look up the payee on the regulator's website and save a screen shot to the file.