Glossary
DKIM: what it is and how it protects your email
DKIM (DomainKeys Identified Mail) is an email authentication method that adds a cryptographic signature to each outgoing message. The receiving server verifies the signature against a public key published in the sender's DNS, confirming the email really comes from that domain and was not altered in transit.
How does DKIM work?
When a message leaves your infrastructure, the sending server computes a hash of selected headers and the body, encrypts it with a private key, and attaches the result as a DKIM-Signature header. The receiving server reads the selector in that header, fetches the matching public key from your DNS, and verifies the signature. If the content was tampered with, or the key does not match, verification fails and the message loses credibility with the filter.
Because the signature travels with the message, DKIM tends to survive forwarding scenarios where SPF fails. It also gives DMARC something to align against: DMARC passes when the signing domain matches the visible "From" domain, which is what ultimately protects your brand from spoofing.
Why it matters in B2B
Mailbox providers treat a valid, aligned DKIM signature as a strong trust signal, and Google and Yahoo's bulk sender requirements have made authentication effectively mandatory since 2024. For outbound teams the implication is simple: without DKIM, deliverability suffers regardless of how good the campaign is, and the domain is easier to impersonate in phishing attempts against your own customers.
Take a hypothetical SaaS company that launches prospecting from a new secondary domain. SPF is set, but nobody publishes the DKIM keys for the sending tool. Messages arrive unsigned, a growing share lands in spam, and the first weeks of the campaign are wasted debugging copy when the issue was a DNS record.
AVANTAI treats DKIM as part of the sending infrastructure of its AI outbound systems: every domain and mailbox is authenticated and tested before sequences launch, so trust is established at the protocol level first.
Frequently asked questions
What is the difference between DKIM and SPF?
SPF validates that the sending server is authorized by the domain; DKIM validates that the message itself is signed by the domain and arrived unmodified. SPF breaks when email is forwarded, while DKIM usually survives forwarding, which is why both are used together.
How do I know if DKIM is configured on my domain?
Check the message headers of an email you sent: a 'DKIM-Signature' header and a 'dkim=pass' result in the authentication summary indicate it works. Your email provider's admin panel and free header analyzers make this easy to verify.
Do I need a separate DKIM key for each sending tool?
Usually yes. Each platform that sends on your behalf signs with its own key pair, published under its own selector in your DNS. That separation is healthy: it lets you rotate or revoke one tool's key without affecting the others.