Add multiple recipients to a recipient list. Double opt-in processes will not be overwritten by other opt-in processes (see <a href="https://support.optimizely.com/hc/en-us/articles/4413192291981#prioritization">Opt-in documentation</a>).

curl --request PUT \
     --url https://api.campaign.episerver.net/rest/{clientId}/recipients/{recipientListId} \
     --header 'accept: application/json'

var myHeaders = new Headers();
myHeaders.append("accept", "application/json");
myHeaders.append("content-type", "application/json");

var requestOptions = {
   method: 'PUT',
   headers: myHeaders,
   redirect: 'follow'
};

fetch("https://api.campaign.episerver.net/rest/{clientId}/recipients/{recipientListId}", requestOptions)
   .then(response => response.text())
   .then(result => console.log(result))
   .catch(error => console.log('error', error));

require "uri"
require "json"
require "net/http"

url = URI("https://api.campaign.episerver.net/rest/{clientId}/recipients/{recipientListId}")

https = Net::HTTP.new(url.host, url.port)
https.use_ssl = true

request = Net::HTTP::Put.new(url)
request["accept"] = "application/json"
request["content-type"] = "application/json"

response = https.request(request)
puts response.read_body

import requests
import json

url = "https://api.campaign.episerver.net/rest/{clientId}/recipients/{recipientListId}"

payload = {}
headers = {
   'accept': 'application/json',
   'content-type': 'application/json'
}

response = requests.request("PUT", url, headers=headers, data=payload)

print(response.text)

// Adding recipients was initiated successfully.
{
  "count": "",
  "failedIds": [
    ""
  ]
}

// The indicated opt-in process is not suitable for adding recipients.