DKIM (DomainKeys Identified Mail)

DKIM (DomainKeys Identified Mail) is an email authentication standard that allows the sending mail server to attach a cryptographic digital signature to outgoing messages. The receiving server retrieves the corresponding public key from the sender's DNS records and uses it to verify the signature. If the signature is valid, the recipient knows the email genuinely came from the claimed domain and was not altered in transit. DKIM works alongside [SPF](/glossary/spf) (Sender Policy Framework) and [DMARC](/glossary/dmarc) (Domain-based Message Authentication, Reporting & Conformance) to form a complete email authentication framework that protects both senders and recipients.

Email remains a primary channel for sharing digital publications, sending lead-capture notifications, and delivering transactional messages. Without DKIM, emails are more likely to be flagged as spam or rejected entirely by recipient mail servers. Major providers like Gmail, Outlook, and Yahoo now require DKIM for bulk senders, and messages without valid signatures face increasingly aggressive filtering. Proper DKIM setup improves deliverability, protects your brand from spoofing (where attackers send emails pretending to be your domain), and builds trust with email providers. For publishers who rely on email to distribute flipbooks and collect leads, DKIM directly affects whether your audience actually sees your messages.

FlipLink sends emails on your behalf for lead-capture notifications, shared publication links, and [email templates](/features/email-templates). These emails are sent through infrastructure that has DKIM configured, meaning every outgoing message carries a valid cryptographic signature. If you use a [custom domain](/features/custom-domains) for your publications and want to send sharing emails from that domain, you configure DKIM DNS records to authorize FlipLink's mail servers to send on your behalf. This ensures recipients see your domain as the verified sender, maximizing inbox placement and maintaining your brand's credibility.