What DKIM tag is used for notes for human readers?
Matthew Whittaker
Co-founder & CTO, Suped
Published 8 Jul 2025
Updated 7 Oct 2025
6 min read
DomainKeys Identified Mail (DKIM) is a critical email authentication standard that helps protect your domain from impersonation and phishing. It works by attaching a digital signature to outgoing emails, allowing recipient mail servers to verify that the email was indeed sent by an authorized sender and that its content hasn't been tampered with in transit. This verification process relies on cryptographic keys and a specialized DNS record published for your domain.
Within a DKIM record in your DNS, various tags are used to convey specific pieces of information about the signature and the signing domain. These tags, often single letters followed by an equal sign and a value, are interpreted by automated systems. However, there's one particular tag designed not for machines, but specifically for human administrators to leave notes or comments. This often-overlooked tag can be incredibly useful for managing complex email infrastructures.
The purpose of DKIM records
DKIM provides a robust method for senders to claim responsibility for an email by cryptographically signing it. This helps receiving mail servers confirm the email's legitimacy, significantly reducing the chances of it being marked as spam or rejected outright. The entire framework, including how these signatures are created and verified, is detailed in RFC 6376, the official specification for DKIM.
A DKIM record is essentially a TXT record published in your domain's DNS. This record contains the public key used to verify the email signature, along with several tags that specify parameters for the signing and verification process. Each tag plays a specific role, from indicating the algorithm used for signing to defining the domain signing the email.
These tags are crucial for the proper functioning of DKIM. Without them, recipient servers wouldn't know how to interpret the signature or which parts of the email to verify. While most tags are highly technical and directly impact email processing, one stands out for its purely informational purpose, aimed solely at helping the people managing these records.
The 'n=' tag for human-readable notes
The DKIM tag used for notes for human readers is the n= tag. This tag is entirely optional and serves no functional purpose in the DKIM verification process. Mail servers and other automated systems will simply ignore its content. Its sole existence is to allow domain administrators to embed human-readable comments or notes directly within the DKIM record itself. Think of it as an inline comment for your DNS configuration.
The value of the n= tag can contain any text string that an administrator deems useful. This could include information about when the record was last updated, who is responsible for it, the purpose of the DKIM key, or any other relevant details that might assist future management or troubleshooting efforts. It’s a simple yet effective way to maintain context within your DNS records.
Example DKIM record with 'n=' tagDNS
selector1._domainkey IN TXT "v=DKIM1; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDgR8n/b...; n=This key is for marketing emails via ESP X, updated 2024-01-15"
As seen in the example above, the n= tag is appended like any other tag in the TXT record. While it won't affect deliverability or authentication outcomes, it greatly enhances the readability and maintainability of your DNS configuration for anyone reviewing it. It is particularly useful when you have multiple DKIM records or when different services use different keys for the same domain.
Why documentation in DKIM records matters
Effective documentation is paramount in complex IT environments, and DNS records are no exception. The n= tag helps prevent confusion and errors, especially in organizations with multiple administrators or a high turnover rate. Without clear notes, it can be challenging to understand the purpose or origin of a specific DKIM key, leading to hesitation in making necessary updates or troubleshooting issues.
Best practices for using the 'n=' tag
Keep it concise: Include essential information without making the record excessively long.
Specify purpose: Indicate which service or email type uses this specific DKIM key. For example, email marketing via SendGrid
Add contact info: If appropriate, include the email address or team responsible for the key.
Date updates: Note the date of creation or last modification for better version control.
Consider a scenario where an email deliverability issue arises, and a new administrator needs to quickly identify the relevant DKIM record among several. A well-placed n= tag can dramatically speed up the diagnostic process, pointing them to the correct key and its context without needing to consult external documentation or colleagues.
While n= provides human notes, other tags like s= (which specifies the selector name) and h= (listing signed header fields) are directly processed by mail servers for authentication. Understanding the function of each tag, both human-oriented and machine-oriented, is crucial for comprehensive DKIM management.
Beyond notes: monitoring and maintaining DKIM
While the n= tag is valuable for internal documentation, it's vital to remember that the effectiveness of DKIM ultimately depends on the correct configuration of all its technical tags. Misconfigurations can lead to DKIM verification failures, impacting your email deliverability and potentially landing your messages in spam folders.
Common DKIM challenges
Misconfigured records: Incorrect key values or improper syntax cause authentication failures.
Expired keys: Forgetting to rotate keys can lead to sudden authentication issues.
Body hash mismatches: Even minor changes to email content can invalidate the signature.
Solutions and best practices
Regular audits: Periodically check your DKIM records for accuracy and freshness.
Automated monitoring: Utilize platforms like Suped for real-time alerts.
DMARC implementation: Leverage DMARC for comprehensive authentication reporting and policy enforcement.
This is where a robust DMARC monitoring tool becomes indispensable. Platforms like Suped provide AI-powered recommendations and real-time alerts to help you identify and fix DKIM issues quickly. This proactive approach ensures your emails are consistently authenticated, maintaining a strong sender reputation and improving deliverability.
Beyond just DKIM, a comprehensive email security strategy involves monitoring SPF and DMARC as well. A unified platform that brings all these elements together provides a holistic view of your email health, preventing your domain from ending up on a blacklist (or blocklist) and ensuring your messages reach their intended inboxes.
Streamlining DKIM management
The n= tag in DKIM records, though technically non-functional for mail servers, plays an important role in the human aspect of email authentication management. It serves as a valuable tool for internal documentation, aiding administrators in understanding, maintaining, and troubleshooting DKIM configurations.
Coupling clear internal documentation with proactive monitoring ensures that your email authentication standards are not only correctly set up but also consistently maintained. Tools like Suped simplify this process, offering comprehensive insights and actionable guidance to optimize your email deliverability and security posture.
email marketing via SendGrid
