Power Automate Send Email via SP HTTPS not sending to specific addresses - http

Question

I have setup a HTTPS request to SharePoint action in PowerAutomate, Using the Uri _api/SP.Utilities.Utility.SendEmail
In the Body, I have 'To': ['myemail#email.com','friendemail#email.com'], along with the rest
In this case the request works and we both receive the email.
However if this changes to ['myemail#email.com','anotherfriendsemail#email.com'] then I receive the email both the other friend does not nor are they listed in the emails To field.
myself and my friend are both owners of the SharePoint site and all parties are part of the same business. The other friend is not a member of the SP site though I tried adding them as an member and then owner and neither worked.
Why does this send to just myself and my friend but not to the other address?
The Error mesage is:
{ "status": 400, "message": "{\"odata.error\":{\"code\":\"-2130242040,Microsoft.SharePoint.SPException\",\"message\":{\"lang\":\"en-US\",\"value\":\"The e-mail message cannot be sent. Make sure the e-mail has a valid recipient.\"}}}\r\nclientRequestId: RecipientID\r\nserviceRequestId: RequestID", "source": "https://hwinc.sharepoint.com/sites/SiteName/_api/SP.Utilities.Utility.SendEmail", "errors": []}
Edit: Full Body Below
Method: Post
Uri: _api/SP.Utilities.Utility.SendEmail
Headers: accept application/json;odata=nometadata
content-type application/json;odata=nometadatae
Body: {
'properties':{
'From': 'Sharpoint_Site_Name#hwinc.onmicrosoft.com',
'To': ['FirstName.LastName#company.com.au','ABC_Sector#company.com.au'],
'Body': '<p>The Following Order has been Approved:<br><br></p>
<table>
<tr> <td>Approver:</td> <td>#{outputs('Start_and_wait_for_an_approval')?['body/responder/displayName']}</td> </tr>
<tr><td>Date of Order:</td><td>#{outputs('Get_response_details')?['body/rfe2e26ab18544ebea75d9b17a5d84af1']}</td></tr>
<tr> <td>Company:</td> <td>#{outputs('Get_response_details')?['body/rcd9f1c32a2364690ae6d6dbbb049a306']}</td> </tr>
<tr> <td>Customer Name:</td> <td>#{outputs('Get_response_details')?['body/r8a29c2d61ac54342a77d1604bd9f796e']}</td> </tr>
<tr> <td>Address:</td> <td>#{outputs('Get_response_details')?['body/r343a56a5c4ac4f55b11e37c5c3a3f0d4']}</td> </tr>
<tr> <td>Estimated Qty:</td> <td>#{outputs('Get_response_details')?['body/r8a28c14eddca4884833443357035c7eb']}</td> </tr>
<tr> <td>Required Mix:</td> <td>#{outputs('Get_response_details')?['body/r2b9c2f804efe49509436a2c44afe4a83']}</td> </tr>
<tr> <td>Boral Plant Name:</td> <td>#{outputs('Get_response_details')?['body/rcc43d77ecc6f4083ac6d3fbf59ffee75']}</td> </tr>
<tr> <td>Plant Code</td> <td>#{outputs('Get_response_details')?['body/r4fd7f3aceb164a67baece47df43933ee']}</td> </tr>
<tr> <td>3rd Party Supplier:</td> <td>#{variables('3rd Party')}</td> </tr>
<tr> <td>Price:</td> <td>#{outputs('Format_Final_Price')?['body']}</td> </tr>
</table>
<p>Kind regards</p>
#{outputs('Start_and_wait_for_an_approval')?['body/responder/displayName']}',
'Subject': 'Urgent! 3rd Party Purchase Order Request'
}
}