Verify all your risky emails at scale. What is a risky email? Risky email is on a catch-all email server where all emails sent to that mailbox are accepted, regardless if the email address actually exists. For example, if Scrubby’s email server was a catch-all, then you could send an email to any email address on scrubby.io’s domain such as to fakeemail@scrubby.io and your email would be accepted. However, this email address doesn’t actually exist.