Summary
A missing or misconfigured DKIM DNS TXT record negatively affects email deliverability by making it difficult to verify the sender's authenticity. Email providers use DKIM as a crucial signal of legitimacy, and its absence raises suspicions of spoofing or phishing, leading to increased spam filtering or outright rejection. Technically, unsigned emails (lacking a DKIM header or having a failed DKIM signature) are similar, but receivers or machine learning algorithms might still penalize them. Implementing DKIM is crucial for establishing trust, protecting sender reputation, and is also a prerequisite for DMARC implementation, thereby enhancing overall email security and deliverability.
Key findings
- Reduced Deliverability: Missing DKIM increases the likelihood of emails being flagged as spam, blocked, deferred, or bounced.
- Compromised Sender Reputation: The absence of DKIM harms sender reputation, leading ISPs to view emails as potentially fraudulent or untrustworthy.
- Authentication Failure: Without DKIM, receiving mail servers cannot reliably verify the sender's identity and domain.
- Spoofing Vulnerability: Missing DKIM increases vulnerability to email spoofing and phishing attacks.
- DMARC Dependency: DKIM (along with SPF) is a necessary prerequisite for implementing DMARC to protect against email attacks.
Key considerations
- Correct Configuration: Ensure DKIM is correctly configured with a valid DNS TXT record to enable proper email authentication.
- Holistic Authentication: Use DKIM in combination with SPF and DMARC for a comprehensive email authentication strategy.
- Reputation Monitoring: Regularly monitor sender reputation to identify and address any issues arising from DKIM implementation (or lack thereof).
- Awareness of Policies: Be aware of the email provider's policies and requirements regarding DKIM and email authentication.
What email marketers say
12 marketer opinions
A missing or improperly configured DKIM DNS TXT record negatively impacts email deliverability. Email providers view the absence of DKIM as a sign of potential untrustworthiness and an increased risk of spam or phishing. Consequently, emails are more likely to be filtered into spam folders, blocked outright, or deferred/bounced. DKIM helps prevent email spoofing and enhances sender reputation by validating email authenticity, a crucial factor in ensuring successful inbox placement.
Key opinions
- Deliverability Impact: Missing DKIM increases the likelihood of emails being flagged as spam or blocked by receiving servers.
- Sender Reputation: The absence of DKIM negatively affects sender reputation, leading ISPs and email providers to view emails as potentially fraudulent.
- Authentication Failure: Without DKIM, receiving mail servers cannot verify the sender's identity.
- Spam Filtering: Emails lacking DKIM are more likely to be directed to spam folders due to heightened suspicion.
- Spoofing Protection: DKIM aids in preventing email spoofing and phishing attacks, which improves sender trust.
- Validation Failure: Failing DKIM authentication results in the same treatment as not having DKIM at all, since it cannot be validated as legitimate.
Key considerations
- DKIM Configuration: Ensure DKIM is properly configured with a valid DNS TXT record to demonstrate email authenticity.
- Email Provider Policies: Be aware of specific email provider policies regarding DKIM, as some may have stricter enforcement than others.
- DMARC Implementation: DKIM is a pre-requisite for DMARC, it's essential for a complete authentication and delivery strategy.
- Holistic Approach: DKIM should be used in conjunction with SPF and DMARC for robust email authentication.
- Reputation Monitoring: Monitor sender reputation to promptly address and mitigate any negative impacts from missing or improperly configured DKIM records.
Marketer view
Email marketer from SocketLabs explains that not using DKIM means your emails are more likely to be flagged as spam. Email providers use DKIM, along with other authentication methods like SPF and DMARC, to assess the legitimacy of email senders.
26 Nov 2023 - SocketLabs
Marketer view
Email marketer from Postmark shares that DKIM authenticates the emails that come from your domain, improving your sender reputation and helping avoid spam filters. Without it, your email is more likely to be marked as spam.
5 Oct 2022 - Postmark
What the experts say
4 expert opinions
Experts emphasize that a missing or invalid DKIM record harms email deliverability and security. Technically, unsigned emails (those without a DKIM header or with a failed DKIM signature) are treated similarly. However, receivers or machine learning filters might still penalize them. DKIM is essential for establishing email authenticity and preventing spam classification, serving as a crucial signal for ISPs. Furthermore, DKIM is a prerequisite for implementing DMARC, highlighting its importance in a comprehensive email security strategy.
Key opinions
- Technical Equivalence: Technically, missing DKIM and failed DKIM are the same: unsigned mail.
- Receiver Interpretation: Receivers and machine learning filters may penalize emails lacking valid DKIM, even if technically considered unsigned.
- Authenticity Signal: DKIM serves as a vital signal for ISPs to verify email legitimacy and prevent spam classification.
- DMARC Dependency: DKIM and SPF are required to implement DMARC, which is important for protecting email against attacks.
Key considerations
- Implement DKIM: Always implement DKIM to provide a valid signature, even if a receiver may not actively check it.
- DMARC strategy: DKIM implementation is a pre-requisite for setting up DMARC policy.
Expert view
Expert from Word to the Wise responds, highlighting that implementing DMARC is not possible without first implementing SPF and DKIM, and without a DMARC policy in place, it's likely that email attacks against an organization will not be prevented effectively.
20 Mar 2022 - Word to the Wise
Expert view
Expert from Email Geeks explains that technically, there's no difference between a mail with no DKIM header and one with a signature that doesn’t validate. Both are unsigned mail. However, a receiver might read something into it, and machine learning filters might recognize it.
25 Mar 2023 - Email Geeks
What the documentation says
5 technical articles
Documentation consistently highlights that DKIM is essential for email deliverability by verifying the sender's identity and preventing spoofing. It provides a cryptographic signature that receiving systems use to confirm that a message was sent by an authorized sender and hasn't been altered in transit. Without a valid DKIM record, emails are more likely to be marked as spam or rejected, as the authenticity of the domain cannot be verified.
Key findings
- Authenticity Verification: DKIM provides a mechanism to verify the authenticity of email senders.
- Spoofing Prevention: DKIM helps prevent email spoofing and phishing attacks by validating the domain from which messages are sent.
- Improved Deliverability: Implementing DKIM improves email deliverability by increasing trust with receiving systems.
- Spam Reduction: Without DKIM, emails are more likely to be marked as spam or rejected.
- Data Integrity: DKIM ensures that the message has not been altered during transit.
Key considerations
- Proper Configuration: Ensure that DKIM records are properly configured and validated to maximize their effectiveness.
- Regular Monitoring: Monitor DKIM implementation to identify and address any potential issues affecting deliverability.
Technical article
Documentation from RFC 6376 (the DKIM standard) details that DKIM provides a cryptographic signature that allows a receiving system to verify that a message was sent by an authorized sender, thereby improving trust and deliverability.
21 Nov 2023 - RFC Editor
Technical article
Documentation from EasyDMARC details that DKIM prevents spoofing by adding a digital signature to email headers, which receiving servers validate, thereby reducing the risk of phishing attacks, and increasing the likelihood your emails are successfully delivered.
21 Oct 2024 - EasyDMARC
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