If you have a lead capture form that asks for the visitor's email address and you want to only receive business emails, you can implement the snippet below on your page.
You will need to edit the highlighted sections from above to contain the exact name of your field and the desired error message that will be shown to visitors who enter a non-business email address. Make sure that you leave the single quotes at the beginning and end of the text that you replace.
If your field is named exactly E-mail you can leave the code unaltered, but if it is named "Email", "Email address", "E-mail address", or if it is in a different language (e.g. "Correo electronico"), you will need to add the exact name of your field in the code, on the fifth row, in order for it to work.