You can switch on verified inquiries on your Settings > For-Sale landing pages page.
When you switch on verified inquiries, anyone making an offer on your domain through your Efty For-Sale landing pages or marketplace site has to verify their inquiry via email. This is a one-click process so we keep things as easy as possible for those submitting an offer on your domain name.

Switching this feature on means that any offer or inquiry that hits your inbox from that moment on is 101% guaranteed coming from the sender whose details you’ll find in the email.
We will still store any non-verified inquiries under Inquiries > All inquiries and notify you with a notification when you sign into your Efty account so you never have to be afraid to miss out on a potential lead. You will, however, only receive email notifications for verified inquiries when you have this feature activated.