diff --git a/README.md b/README.md
index 05bdc6e..276f6c9 100644
--- a/README.md
+++ b/README.md
@@ -195,7 +195,7 @@ To use the [Transactional API](https://customer.io/docs/transactional-api), inst
 SendEmailRequest requires:
 * `transactional_message_id`: the ID of the transactional message you want to send, or the `body`, `from`, and `subject` of a new message.
 * `to`: the email address of your recipients 
-* an `identifiers` object containing the `id` of your recipient. If the `id` does not exist, Customer.io will create it.
+* an `identifiers` object containing the `email` and/or `id` of your recipient. If the person you reference by email or ID does not exist, Customer.io creates them.
 * a `message_data` object containing properties that you want reference in your message using Liquid.
 * You can also send attachments with your message. Use `attach` to encode attachments.
 
@@ -218,7 +218,7 @@ request = SendEmailRequest(
     ]
   },
   identifiers={
-    "id": "2",
+    "email": "person@example.com",
   }
 )