curl --request POST \
  --url https://api.getmaito.com/v1/newsletter/subscribers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "email": "reader@example.com",
  "sourceType": "api",
  "source": "custom_website",
  "optInAttestation": true
}
'

{
  "data": {
    "id": "<string>",
    "workspaceId": "<string>",
    "accountSetId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "emailNormalized": "jsmith@example.com",
    "emailOriginal": "<string>",
    "subscribedAt": "<string>",
    "createdAt": "<string>",
    "updatedAt": "<string>",
    "source": "<string>",
    "sourceIssueId": "<string>",
    "sourcePostId": "<string>",
    "sourceCtaLinkId": "<string>",
    "sourceVisitorId": "<string>",
    "unsubscribedAt": "<string>"
  }
}