# Set up reverse DNS ## API Overview 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](/docs/sendgrid/ui/account-and-settings/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 section of the Twilio SendGrid App](https://app.sendgrid.com/settings/sender_auth). For more about Reverse DNS, see ["How to set up reverse DNS"](/docs/sendgrid/ui/account-and-settings/how-to-set-up-reverse-dns/) in the Twilio SendGrid documentation. ## Operation overview ```json {"path":"https://api.sendgrid.com/v3/whitelabel/ips","method":"post","servers":[{"url":"https://api.sendgrid.com","description":"for global users and subusers"},{"url":"https://api.eu.sendgrid.com","description":"for EU regional subusers"}]} ``` **This endpoint allows you to set up reverse DNS.** ## Operation details ### Authentication API Key ### Headers ```json [{"in":"header","name":"Authorization","required":true,"default":"Bearer <>","schema":{"type":"string"}},{"name":"on-behalf-of","in":"header","description":"The `on-behalf-of` header allows you to make API calls from a parent account on behalf of the parent's Subusers or customer accounts. You will use the parent account's API key when using this header. When making a call on behalf of a customer account, the property value should be \"account-id\" followed by the customer account's ID (e.g., `on-behalf-of: account-id `). When making a call on behalf of a Subuser, the property value should be the Subuser's username (e.g., `on-behalf-of: `). See [**On Behalf Of**](/docs/sendgrid/api-reference/how-to-use-the-sendgrid-v3-api/on-behalf-of) for more information.","required":false,"schema":{"type":"string"},"refName":"#/components/parameters/OnBehalfOf","modelName":"__components_parameters_OnBehalfOf"}] ``` ### Request body ```json {"schema":{"type":"object","required":["ip","domain"],"example":{"ip":"192.168.1.1","subdomain":"email","domain":"example.com"},"properties":{"ip":{"type":"string","description":"The IP address for which you want to set up reverse DNS."},"subdomain":{"type":"string","description":"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":{"type":"string","description":"The root, or sending, domain that will be used to send message from the IP address."}}},"encodingType":"application/json"} ``` ### Responses ```json [{"responseCode":"201","schema":{"description":"","content":{"application/json":{"schema":{"title":"Reverse DNS","type":"object","required":["id","ip","rdns","users","domain","valid","legacy","a_record"],"example":{"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"}},"refName":"ReverseDns","modelName":"ReverseDns","properties":{"id":{"type":"integer","description":"The ID of the Reverse DNS."},"ip":{"type":"string","description":"The IP address that this Reverse DNS was created for."},"rdns":{"type":"string","description":"The reverse DNS record for the IP address. This points to the Reverse DNS subdomain."},"users":{"type":"array","description":"The users who are able to send mail from the IP address.","items":{"type":"object","required":["username","user_id"],"properties":{"username":{"type":"string","description":"The username of a user who can send mail from the IP address."},"user_id":{"type":"integer","description":"The ID of a user who can send mail from the IP address."}}}},"subdomain":{"type":"string","description":"The subdomain created for this reverse DNS. This is where the rDNS record points."},"domain":{"type":"string","description":"The root, or sending, domain."},"valid":{"type":"boolean","description":"Indicates if this is a valid Reverse DNS."},"legacy":{"type":"boolean","description":"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."},"last_validation_attempt_at":{"type":"integer","description":"A Unix epoch timestamp representing the last time of a validation attempt."},"a_record":{"type":"object","required":["valid","type","host","data"],"properties":{"valid":{"type":"boolean","description":"Indicates if the a_record is valid."},"type":{"type":"string","description":"The type of DNS record."},"host":{"type":"string","description":"This is the web address that will be mapped to the IP address."},"data":{"type":"string","description":"The IP address being set up with Reverse DNS."}}}}},"examples":{"response":{"value":{"id":123,"ip":"192.168.1.2","rdns":"o1.email.example.com","users":[],"subdomain":"email","domain":"example.com","valid":true,"legacy":false,"a_record":{"valid":true,"type":"a","host":"o1.email.example.com","data":"192.168.1.2"}}}}}}}}] ``` Set up reverse DNS ```js const client = require("@sendgrid/client"); client.setApiKey(process.env.SENDGRID_API_KEY); const data = { ip: "192.168.1.1", subdomain: "email", domain: "example.com", }; const request = { url: `/v3/whitelabel/ips`, method: "POST", body: data, }; client .request(request) .then(([response, body]) => { console.log(response.statusCode); console.log(response.body); }) .catch((error) => { console.error(error); }); ``` ```python import os from sendgrid import SendGridAPIClient sg = SendGridAPIClient(os.environ.get("SENDGRID_API_KEY")) data = {"ip": "192.168.1.1", "subdomain": "email", "domain": "example.com"} response = sg.client.whitelabel.ips.post(request_body=data) print(response.status_code) print(response.body) print(response.headers) ``` ```csharp using System; using System.Collections.Generic; using System.Threading.Tasks; using SendGrid; public class Program { public static async Task Main() { string apiKey = Environment.GetEnvironmentVariable("SENDGRID_API_KEY"); var client = new SendGridClient(apiKey); var data = @"{ ""ip"": ""192.168.1.1"", ""subdomain"": ""email"", ""domain"": ""example.com"" }"; var response = await client.RequestAsync( method: SendGridClient.Method.POST, urlPath: "whitelabel/ips", requestBody: data); Console.WriteLine(response.StatusCode); Console.WriteLine(response.Body.ReadAsStringAsync().Result); Console.WriteLine(response.Headers.ToString()); } } ``` ```java import com.sendgrid.*; import java.io.IOException; import org.json.JSONObject; import java.util.HashMap; public class Example { public static void main(String[] args) throws IOException { try { SendGrid sg = new SendGrid(System.getenv("SENDGRID_API_KEY")); Request request = new Request(); request.setMethod(Method.POST); request.setEndpoint("/whitelabel/ips"); request.setBody(new JSONObject(new HashMap() { { put("ip", "192.168.1.1"); put("subdomain", "email"); put("domain", "example.com"); } }).toString()); Response response = sg.api(request); System.out.println(response.getStatusCode()); System.out.println(response.getBody()); System.out.println(response.getHeaders()); } catch (IOException ex) { throw ex; } } } ``` ```go package main import ( "fmt" "github.com/sendgrid/sendgrid-go" "os" ) func main() { apiKey := os.Getenv("SENDGRID_API_KEY") host := "https://api.sendgrid.com" request := sendgrid.GetRequest(apiKey, "/v3/whitelabel/ips", host) request.Method = "POST" request.Body = []byte(`{ "ip": "192.168.1.1", "subdomain": "email", "domain": "example.com" }`) response, err := sendgrid.API(request) if err != nil { fmt.Println(err.Error()) os.Exit(1) } else { fmt.Println(response.StatusCode) fmt.Println(response.Body) fmt.Println(response.Headers) } } ``` ```php /sendgrid-php.php'; $apiKey = getenv("SENDGRID_API_KEY"); $sg = new \SendGrid($apiKey); $request_body = json_decode('{ "ip": "192.168.1.1", "subdomain": "email", "domain": "example.com" }'); try { $response = $sg->client ->whitelabel() ->ips() ->post($request_body); print $response->statusCode() . "\n"; print_r($response->headers()); print $response->body() . "\n"; } catch (Exception $ex) { echo "Caught exception: " . $ex->getMessage(); } ``` ```ruby require 'sendgrid-ruby' include SendGrid sg = SendGrid::API.new(api_key: ENV['SENDGRID_API_KEY']) data = JSON.parse('{ "ip": "192.168.1.1", "subdomain": "email", "domain": "example.com" }') response = sg.client.whitelabel.ips.post(request_body: data) puts response.status_code puts response.headers puts response.body ``` ```bash curl -X POST "https://api.sendgrid.com/v3/whitelabel/ips" \ --header "Authorization: Bearer $SENDGRID_API_KEY" \ --header "Content-Type: application/json" \ --data '{"ip": "192.168.1.1", "subdomain": "email", "domain": "example.com"}' ```