Automatically sending newsletter subscribers from InstaWP to Mailchimp

This GraphQL query captures the email from the visitors who ticked the "Subscribe to mailing list" checkbox from InstaWP (when creating a new sandbox site), and subscribes this email to a Mailchimp list:

query HasSubscribedToNewsletter {
hasSubscriberOptin: _httpRequestHasParam(name: "marketing_optin")
subscriberOptin: _httpRequestStringParam(name: "marketing_optin")
isNotSubscriberOptinNAValue: _notEquals(value1: $__subscriberOptin, value2: "NA")
subscribedToNewsletter: _and(values: [$__hasSubscriberOptin, $__isNotSubscriberOptinNAValue])
@export(as: "subscribedToNewsletter")

query MaybeCreateContactOnMailchimp
@depends(on: "HasSubscribedToNewsletter")
@include(if: $subscribedToNewsletter)
subscriberEmail: _httpRequestStringParam(name: "email")

mailchimpUsername: _env(name: "MAILCHIMP_API_CREDENTIALS_USERNAME")
mailchimpPassword: _env(name: "MAILCHIMP_API_CREDENTIALS_PASSWORD")

mailchimpListMembersJSONObject: _sendJSONObjectItemHTTPRequest(input: {
url: "{listCode}/members",
method: POST,
options: {
auth: {
username: $__mailchimpUsername,
password: $__mailchimpPassword
json: {
email_address: $__subscriberEmail,
status: "subscribed"

And define in wp-config.php:

define( 'MAILCHIMP_API_CREDENTIALS_USERNAME', '{ username }' );
define( 'MAILCHIMP_API_CREDENTIALS_PASSWORD', '{ password }' );

Step by step analysis of the GraphQL query permalink

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Extensions referenced in this recipe permalink

(They are all included in “Application Glue & Automator” Bundle, “All Extensions” Bundle)