Paste any email address and find out if the mailbox exists, whether the domain is a throwaway service, and whether it shows the patterns we see in fake signups.
We ask the receiving mail server about the address without sending anything to it. If the server says the mailbox is not there, every email you send it will bounce and every lead attached to it is a dead end.
Services that hand out ten-minute inboxes are behind a huge share of fake signups. We keep a list of over a hundred thousand of these domains and refresh it constantly. If an address comes from one, the person behind it did not want to hear from you again.
A domain registered last week that is already submitting forms is a bad sign. Fraud operations burn through fresh domains because the old ones get blocked. Domain age is one of the strongest single signals there is.