Python Mailgun API Not Sending Email

When running the program the email does not appear in my mailbox, I do not get any errors.

import requests
def send_simple_message():
    return requests.post(
        "https://api.mailgun.net/v3/sandbox26ec5a4187a942f6a834bb53d77d2b31.mailgun.org/messages",
        auth=("api", "API_KEY"),
        data={"from": "Excited User <mailgun@sandbox26ec5a4187a942f6a834bb53d77d2b31.mailgun.org>",
            "to": ["MY_EMAIL", "MY_SECOND_EMAIL"],
            "subject": "Hello",
            "text": "Testing some Mailgun awesomness!"})