DKIM Record Reference
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This article serves as a reference for the formal structure, restrictions, and key technical details of a DKIM (DomainKeys Identified Mail) record.
DKIM Record Format
A DKIM record is not a unique DNS record type with its own number. Instead, it is a specially formatted TXT record published in DNS. Some providers have you add a CNAME record instead, pointing to a TXT record they host. The record’s format and tags are specified in RFC 6376.
The DKIM record is always published on a specific subdomain known as the selector record. This is a combination of a selector, the literal _domainkey, and the domain name.
The format is: <selector>._domainkey.<domain.name>
The value of the TXT record contains a series of tags that define the public key and other policy information. Here are the most common tags:
| Tag | Description | Value |
|---|---|---|
v |
Version: Indicates the version of DKIM in use. | Must be DKIM1. |
k |
Key type: Indicates the public key algorithm used. | Usually rsa (the default). ed25519 is also defined. |
p |
Public key: Used to verify the email’s signature. | A Base64-encoded string representing the public key. |
t |
Flags: A colon-separated list of flags. |
y (test mode) or s (strict: no subdomains). |
Example of a DKIM TXT record:
selector1._domainkey.example.com. IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQD..."
DKIM record restrictions and notes
Record type: DKIM is typically configured using a TXT record, which has a type code of 16.
Selector: The selector is a name chosen by your email provider to create a unique DNS record. This allows multiple keys to exist under a single domain for different services or key rotation.
Content: The public key is often longer than the 255 characters a single TXT string can hold. You can paste the whole value into DNSimple as one string: DNSimple’s name servers split it into 255-character strings when they answer.
DKIM record management
You can manage DKIM records in DNSimple by creating a TXT record with the _domainkey selector provided by your email service provider.
Example DNSimple configuration:
Name: selector1._domainkey (The domain is appended automatically).
Content: "v=DKIM1; p=..."
Have more questions?
If you have additional questions or need any assistance with your DKIM records, just contact support, and we will be happy to help. You can also read more about DNS hosting at DNSimple.