Send Email to contact from Rest API resulting in { message: "General Error" }

I have been attempting to send an email to a single contact for password reset proposes using the Keap REST API. Ive got all the authentication working, formatted the body and have tried posting to[access_token] Where “[access_token]” was replaced with my actual token with this body:

“address_field”: “EMAIL1”,
“contacts”: [
“subject”: “Test”,
“html_content”: “PGgxPlRFU1Q8L2gxPg==”,
“user_id”: 2

But when sending the request, it always results in a 500 { message: "General Error" }

I’ve tried to look up the error and have read through numerous forum posts here. non of which are working. I also tried manually confirming the email for a contact; no luck with that either. I got the same result of the “General Error”.

Is there something I’m missing in the body? Does the API not allow emails to be sent? Or does PostMan simply not properly format the request to Keap? Do the contacts require special attention before an email can be sent? (When being created the contact’s email defaults to “Unconfirmed”). What actions do I need to take to allow emails to be sent properly?