Sending Email via MS 365 Graph

Help & Questions
1

Hi Support

We are encountering an issue when attempting to send email via the Microsoft Graph API.

Error details:

Exception: Unable to send email message: Client error: 
`POST https://graph.microsoft.com/v1.0/users('Support%40mpr-it.co.uk')/sendMail` 
resulted in a `400 Bad Request` response:

{
  "error": {
    "code": "InvalidInternetMessageHeader",
    "message": "The internet message header name 'In-Reply-To' should start with 'x-' or 'X-'."
  }
}

The send mail 

![image|690x166](upload://7GsWnXz5vIBgiVFEbvM8OxLYcEe.png)




The message history is https://console.uk1.mspintegrations.com/email2at/advanced/history/17791919023910002t9p

Thank you