The DKIM legend lists all supported tags with their default values and short explanation. Refer to RFC6376 for more in depth information. As the RFC states any unsupported tags MAY be present and MUST be ignored.
|v||Version||DKIM1||Version of the DKIM key record (plain-text; RECOMMENDED). This tag MUST be the first tag in the record if present. Warning: some ISPs may mark the DKIM authentication check as neutral if the version tag is invalid.|
|h||Hash algorithms||* (allow all)||Acceptable hash algorithms (plain-text; OPTIONAL). A colon-separated list of hash algorithms that might be used. Unrecognized algorithms MUST be ignored. The currently recognized algorithms are "sha1" and "sha256".|
|k||Key type||rsa||Key type (plain-text; OPTIONAL). Unrecognized key types MUST be ignored. Currently only "rsa" is recognized.|
|n||Notes||(empty)||Notes that might be of interest to a human (OPTIONAL). Not interpreted in any way.|
|p||Public key||(none)||Public-key data (base64; REQUIRED). An empty value means that this public key has been revoked. This is the only required tag.|
|s||Service type||* (allow all)||Service Type (plain-text; OPTIONAL). A colon-separated list of service types to which this record applies. Unrecognized service types MUST be ignored. Currently only "email" is recognized.|
|t||Flags||(no flags set)||
Flags (plain-text; OPTIONAL). A colon-separated list of names.
Unrecognized flags MUST be ignored. The defined flags are as follows:
"y" - this domain is testing DKIM (test mode)
"s" - verifiers MUST check for domain alignment (strict mode)