DKIM ( DomainKeys Identified Mail ) is a way of checking that the emails you receive haven’t been interfered with en route to you, and that they genuinely do come from the email addresses that they claim to be from. It uses a digitally signed private key that is exchanged between sender and recipient to verify that its bona fide. DKIM helps to protect you from things like spam and phishing attacks—which try to get hold of personal information like your bank account numbers and credit card details.