Summary
The absence of DKIM in an email authentication setup where SPF and DMARC are already aligned presents a nuanced situation. While some experts suggest the immediate impact on deliverability might be minimal in common scenarios, the overwhelming consensus, backed by email marketers and documentation, emphasizes the importance of DKIM for enhanced security and long-term deliverability. DKIM provides message integrity verification, ensuring emails haven't been tampered with, and helps authenticate the sender, which can improve reputation and inbox placement. It's particularly crucial for forwarded messages, as SPF checks may fail in such cases, making DKIM the primary authenticator. Without DKIM, emails may be more susceptible to spam filtering, and the lack of this industry-standard protocol can raise red flags with mailbox providers. Ultimately, implementing DKIM alongside SPF and DMARC is recommended for a robust and resilient email authentication strategy.
Key findings
- Enhanced Security: DKIM offers an additional layer of security and message integrity verification beyond SPF and DMARC.
- Reputation Impact: The absence of DKIM can negatively impact sender reputation, as it's an expected industry standard.
- Forwarding Vulnerability: DKIM becomes critical for forwarded emails, which may not pass SPF checks.
- Deliverability Risks: Without DKIM, emails are more vulnerable to being marked as spam and may face deliverability issues.
- Comprehensive Authentication: DKIM strengthens the overall email authentication framework when used in conjunction with SPF and DMARC.
Key considerations
- DKIM Implementation: Prioritize the implementation of DKIM, even if SPF and DMARC are already in place, to enhance email security and long-term deliverability.
- Forwarding Handling: Address forwarding scenarios by ensuring DKIM is properly configured to authenticate messages that may fail SPF checks.
- Monitoring Reputation: Monitor sender reputation closely to identify any negative impacts from the absence of DKIM and take corrective action.
- Industry Standards Compliance: Adhere to industry best practices by implementing DKIM, as its absence may raise deliverability concerns with mailbox providers.
- Regular Auditing: Regularly audit email authentication configurations to ensure DKIM, SPF, and DMARC are properly set up and maintained.
What email marketers say
9 marketer opinions
While SPF and DMARC are essential for email authentication, the absence of DKIM, even when these are aligned, can still negatively impact email deliverability. DKIM provides an additional layer of security and ensures message integrity, which can improve sender reputation and inbox placement. Email providers may view emails without DKIM as less trustworthy, potentially leading to filtering as spam, especially when messages are forwarded and SPF checks fail.
Key opinions
- Improved Deliverability: DKIM provides an extra layer of security, bolstering deliverability even when SPF and DMARC are aligned.
- Enhanced Authentication: DKIM ensures message integrity and verifies the sender's authenticity, strengthening the overall authentication process.
- Reputation Impact: The lack of DKIM may negatively impact sender reputation, as it is an industry standard expected by mailbox providers.
- Forwarding Vulnerability: Forwarded emails may not pass SPF checks, making DKIM critical for maintaining deliverability in such cases.
- Increased Trustworthiness: Email providers may view emails without DKIM as less trustworthy, potentially leading to increased spam filtering.
Key considerations
- Implement DKIM: Even with SPF and DMARC in place, implement DKIM to provide a robust email security framework and improve deliverability.
- Monitor Reputation: Monitor sender reputation to ensure that the absence of DKIM is not negatively impacting email deliverability.
- Forwarding Scenarios: Consider the impact on forwarded emails, where SPF may fail, and ensure DKIM is properly configured to mitigate deliverability issues.
- Industry Standards: Adhere to industry standards by implementing DKIM, as its absence may raise red flags with mailbox providers.
- Regular Review: Regularly review and update email authentication settings to adapt to evolving deliverability requirements and best practices.
Marketer view
Email marketer from Email Geeks states that DKIM is important to improve deliverability.
26 Oct 2024 - Email Geeks
Marketer view
Email marketer from SocketLabs shares that forwarded messages may not pass SPF. This increases the importance of ensuring DKIM is correctly setup, otherwise the email will fail all email security checks.
16 Feb 2022 - SocketLabs
What the experts say
3 expert opinions
While SPF and DMARC provide essential email authentication, expert opinions vary on the necessity of DKIM when these are already in place. Some experts suggest that in common cases, the absence of DKIM may not significantly impact deliverability if SPF is passing and DMARC is aligned. However, they also emphasize that implementing DKIM is still a best practice. It provides an additional layer of authentication, enhances message integrity, and strengthens security, particularly for forwarded messages that may fail SPF checks. DKIM also contributes to a more robust reputation.
Key opinions
- Deliverability Impact: The immediate impact on deliverability may be minimal in common cases if SPF is passing and DMARC is aligned, but DKIM absence can create longer term issues.
- Enhanced Security: DKIM offers an additional layer of authentication and helps maintain message integrity throughout the delivery chain.
- Best Practice: Signing all outbound emails with DKIM is recommended as a best practice, even with existing SPF and DMARC configurations.
- Forwarding Considerations: DKIM becomes more crucial for forwarded messages that might not pass SPF checks, ensuring continued authentication.
- Robust Reputation: Implementing DKIM alongside SPF and DMARC contributes to a more robust sender reputation.
Key considerations
- Implementation: Even with SPF and DMARC functioning, consider implementing DKIM to enhance email security and message integrity.
- Forwarding: Prioritize DKIM implementation to handle scenarios where messages are forwarded, and SPF checks may fail.
- Risk Assessment: Assess the risks associated with not having DKIM, particularly concerning message integrity and long-term deliverability.
- Configuration: Ensure proper configuration of DKIM, SPF, and DMARC to create a comprehensive email authentication strategy.
- Monitoring: Monitor email deliverability and sender reputation to determine if DKIM implementation is required for optimal performance.
Expert view
Expert from Spam Resource (summarising M3AAWG documentation) explains that DKIM signing all outbound email is a best practice even with SPF and DMARC as it provides an additional layer of authentication and helps ensure message integrity throughout the delivery chain.
8 Dec 2024 - Spam Resource
Expert view
Expert from Email Geeks explains that if SPF is passing and DMARC aligned, lack of DKIM won’t have any effect on deliverability in the common case, however it is worth looking at adding to make reputation and DMARC more robust against forwarding.
14 Feb 2024 - Email Geeks
What the documentation says
4 technical articles
Documentation indicates that while SPF and DMARC are crucial for email authentication, DKIM plays a vital role in verifying the source and integrity of email messages. Even when SPF passes and DMARC is aligned, the absence of DKIM can reduce the overall strength of authentication, making emails more susceptible to tampering and potentially impacting deliverability. It is strongly recommended to implement DKIM to ensure robust authentication and mitigate the risk of certain attacks, as it enhances trust and helps maintain message integrity.
Key findings
- Message Integrity: DKIM provides message integrity verification, ensuring that emails have not been altered in transit.
- Source Verification: DKIM verifies the source of email messages, confirming they were sent by an authorized domain.
- Reduced Authentication: The absence of DKIM, even with SPF passing, reduces the overall strength of email authentication.
- Increased Vulnerability: Without DKIM, emails are more vulnerable to tampering and certain types of attacks.
- Deliverability Impact: Failure to implement DKIM can impact email deliverability, potentially resulting in messages being flagged as spam.
Key considerations
- Implementation: Implement DKIM alongside SPF and DMARC to establish a comprehensive email authentication strategy.
- Risk Mitigation: Mitigate the risk of tampering and certain attacks by ensuring that DKIM is properly configured.
- Trust Enhancement: Enhance trust by implementing DKIM, which confirms the authenticity and integrity of email messages.
- Authentication Strength: Recognize that SPF and DMARC alone may not provide sufficient authentication and that DKIM adds an essential layer.
- Deliverability Monitoring: Monitor email deliverability to determine the impact of DKIM implementation on inbox placement and spam filtering.
Technical article
Documentation from Microsoft explains that even if the email passes SPF and DMARC checks it still requires the use of DKIM for better email deliverability. They suggest it can still impact your deliverability if you don't implement DKIM.
7 Jul 2022 - Microsoft
Technical article
Documentation from ietf.org explains that DKIM provides a method for verifying the source and integrity of email messages, allowing recipients to confirm that the message was sent by an authorized domain and has not been altered in transit. While not explicitly stating the impact without it when SPF/DMARC are present, it highlights DKIM's core function in authentication.
29 May 2023 - ietf.org
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