DKIM (DomainKeys Identified Mail)
DKIM (DomainKeys Identified Mail) is an email-authentication method that attaches a cryptographic signature to each message. The receiving server verifies the signature against a public key in the sender's DNS, proving the message wasn't altered in transit and genuinely came from the signing domain.
How it works
Your mail server signs outgoing messages with a private key; you publish the matching public key as a DNS TXT record at a named selector. Receivers fetch the key and validate the signature.
Why it matters
DKIM survives forwarding better than SPF and is required (with SPF and DMARC) by Gmail and Yahoo for bulk senders. Valid DKIM alignment is a core trust signal for inbox placement.
How Autocloz handles it
Autocloz monitors DKIM signing and alignment for every sending domain and surfaces broken or unaligned selectors in the deliverability view so you fix them before sending volume.
FAQ
What is DKIM alignment?
Alignment means the domain in the DKIM signature matches the visible From domain. DMARC passes when SPF or DKIM is aligned; unaligned signatures still fail DMARC.
Related terms
Cold email deliverability is the share of your outbound cold emails that actually reach the recipient's inbox (not spam, not blocked). It depends on domain authentication (SPF, DKIM, DMARC), sender reputation, mailbox warmup, list hygiene and content — not just whether the email was 'sent'.
DMARC (Domain-based Message Authentication, Reporting & Conformance) is an email standard that tells receiving mail servers what to do with messages that fail SPF or DKIM checks — and sends you reports. It prevents spoofing of your domain and is now effectively required by Gmail and Yahoo for bulk senders.
SPF (Sender Policy Framework) is an email-authentication standard that lets a domain owner publish, in DNS, the list of mail servers allowed to send email on the domain's behalf. Receiving servers check the sending IP against that list to help detect spoofing and decide whether to trust the message.
Mailbox warmup is the practice of gradually increasing a new email account's sending volume while generating positive engagement (opens, replies, moving mail out of spam) so mailbox providers build trust in the sender before real campaigns ramp up.