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Reverse DNS

Reverse DNS (formerly IP Whitelabel) allows mailbox providers to verify the sender of an email by performing a reverse DNS lookup upon receipt of the emails you send.

Reverse DNS is available for dedicated IP addresses only.

When setting up reverse DNS, Twilio SendGrid will provide an A Record (address record) for you to add to your DNS records. The A Record maps your sending domain to a dedicated Twilio SendGrid IP address.

A Reverse DNS consists of a subdomain and domain that will be used to generate a reverse DNS record for a given IP address. Once Twilio SendGrid has verified that the appropriate A record for the IP address has been created, the appropriate reverse DNS record for the IP address is generated.

You can also manage your reverse DNS settings in the Sender Authentication setion of the Twilio SendGrid App.

For more about Reverse DNS, see "How to set up reverse DNS" in the Twilio SendGrid documentation.

Validate a reverse DNS record

POST /whitelabel/ips/{id}/validate

This endpoint allows you to validate a reverse DNS record.

Always check the valid property of the response’s validation_results.a_record object. This field will indicate whether it was possible to validate the reverse DNS record. If the validation_results.a_record.valid is false, this indicates only that Twilio SendGrid could not determine the validity your reverse DNS record — it may still be valid.

If validity couldn’t be determined, you can check the value of validation_results.a_record.reason to find out why.

You can retrieve the IDs associated with all your reverse DNS records using the "Retrieve all reverse DNS records" endpoint.

Authentication

  • API Key

Headers

Authorization
string
default: Bearer <<YOUR_API_KEY_HERE>>
required
on-behalf-of
string
default: The subuser's username. This header generates the API call as if the subuser account was making the call.

Path Parameters

id
string

The ID of the reverse DNS record that you would like to validate.

default: None
required

Responses

object
id
integer

The ID of the reverse DNS record.

required
valid
boolean

Indicates if the reverse DNS record is valid.

Allowed Values: true, false
required
validation_results
object

The specific results of the validation.

required
a_record
object
valid
boolean

Indicates if the reverse DNS record could be validated.

Allowed Values: true, false
required
reason
string or null

The reason the reverse DNS record could not be validated. Is null if the reverse DNS record was validated.

required
object
errors
array[object]

The error messages for the failed validation.

required
message
string

A message describing why the reverse DNS could not be validated.

object
errors
array[object]

The error messages for the failed validation.

required
message
string

A message describing why the IP whitelabel could not be validated.

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