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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.

Set up reverse DNS

POST /whitelabel/ips

This endpoint allows you to set up reverse DNS.

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.

Request Body

object
ip
string

The IP address for which you want to set up reverse DNS.

required
subdomain
string

The subdomain that will be used to send emails from the IP address. This should be the same as the subdomain used to set up an authenticated domain.

domain
string

The root, or sending, domain that will be used to send message from the IP address.

required
{
  "ip": "192.168.1.1",
  "subdomain": "email",
  "domain": "example.com"
}

Responses

object
id
integer

The ID of the Reverse DNS.

required
ip
string

The IP address that this Reverse DNS was created for.

required
rdns
string

The reverse DNS record for the IP address. This points to the Reverse DNS subdomain.

required
users
array[object]

The users who are able to send mail from the IP address.

required
username
string

The username of a user who can send mail from the IP address.

user_id
integer

The ID of a user who can send mail from the IP address.

subdomain
string

The subdomain created for this reverse DNS. This is where the rDNS record points.

domain
string

The root, or sending, domain.

required
valid
boolean

Indicates if this is a valid Reverse DNS.

required
legacy
boolean

Indicates if this Reverse DNS was created using the legacy whitelabel tool. If it is a legacy whitelabel, it will still function, but you'll need to create a new Reverse DNS if you need to update it.

required
last_validation_attempt_at
integer

A Unix epoch timestamp representing the last time of a validation attempt.

a_record
object
required
valid
boolean

Indicates if the a_record is valid.

required
type
string

The type of DNS record.

required
host
string

This is the web address that will be mapped to the IP address.

required
data
string

The IP address being set up with Reverse DNS.

required
{
  "id": 1,
  "ip": "192.168.1.1",
  "rdns": "o1.email.example.com",
  "users": [
    {
      "username": "john@example.com",
      "user_id": 7
    },
    {
      "username": "jane@example.com",
      "user_id": 8
    }
  ],
  "subdomain": "email",
  "domain": "example.com",
  "valid": true,
  "legacy": false,
  "a_record": {
    "valid": true,
    "type": "a",
    "host": "o1.email.example.com",
    "data": "192.168.1.1"
  }
}
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