Microsoft Graph API Error – At least one recipient is not valid., A message can't be sent because it contains no recipients

I am using microsoft Graph API to send email. I have set up my application in Entra.
I am first saving a draft using API – https://graph.microsoft.com/v1.0/me/messages

Which gave me response –

{
"@odata.context": "https://graph.microsoft.com/v1.0/$metadata#users('02720573-7ab2-4d63-b61b-97da9c881a5c')/messages/$entity",
"@odata.etag": "W/\"CQAAABYAAAAtK9qWA0ShRKzuJQcuV7P9AAAEfmZ6\"",
"id": "AAMkADg1ZmUzYWU2LWNmNTEtNDNkYS1iMTMxLTE2ZWE3NThjOTJlNQBGAAAAAABc1YMkdg4qT74XBMUltssfBwAtK9qWA0ShRKzuJQcuV7P9AAAAAAEPAAAtK9qWA0ShRKzuJQcuV7P9AAAEglX3AAA=",
"createdDateTime": "2024-02-09T09:52:12Z",
"lastModifiedDateTime": "2024-02-09T09:52:12Z",
"changeKey": "CQAAABYAAAAtK9qWA0ShRKzuJQcuV7P9AAAEfmZ6",
"categories": [],
"receivedDateTime": "2024-02-09T09:52:12Z",
"sentDateTime": "2024-02-09T09:52:12Z",
"hasAttachments": false,
"internetMessageId": "<DS0PR19MB7345B954A5D38B99DA52E775A24B2@DS0PR19MB7345.namprd19.prod.outlook.com>",
"subject": "5Feb",
"bodyPreview": "5Feb",
"importance": "normal",
"parentFolderId": "AQMkADg1ZmUzYWU2LWNmNTEtNDNkYS1iMTMxLTE2ZWE3NThjOTJlNQAuAAADXNWDJHYOKk__FwTFJbbLHwEALSvalgNEoUSs7iUHLlez-QAAAgEPAAAA",
"conversationId": "AAQkADg1ZmUzYWU2LWNmNTEtNDNkYS1iMTMxLTE2ZWE3NThjOTJlNQAQAAeqIgr5i85AkWtRk-vVNEI=",
"conversationIndex": "AQHaWz2nB6oiCvmLzkCRa1GT+9U0Qg==",
"isDeliveryReceiptRequested": false,
"isReadReceiptRequested": false,
"isRead": true,
"isDraft": true,
"webLink": "https://outlook.office365.com/owa/?ItemID=AAMkADg1ZmUzYWU2LWNmNTEtNDNkYS1iMTMxLTE2ZWE3NThjOTJlNQBGAAAAAABc1YMkdg4qT74XBMUltssfBwAtK9qWA0ShRKzuJQcuV7P9AAAAAAEPAAAtK9qWA0ShRKzuJQcuV7P9AAAEglX3AAA%3D&exvsurl=1&viewmodel=ReadMessageItem",
"inferenceClassification": "focused",
"body": {
    "contentType": "text",
    "content": "5Feb"
},
"toRecipients": [
    {
        "emailAddress": {
            "name": "nileshkemse7@gmail.com",
            "address": "nileshkemse7@gmail.com"
        }
    }
],
"ccRecipients": [],
"bccRecipients": [],
"replyTo": [],
"flag": {
    "flagStatus": "notFlagged"
}

}

Now when I try to send this draft mail using – https://graph.microsoft.com/v1.0/users/02720573-7ab2-4d63-b61b-97da9c881a5c/sendMail

It gives me following error

{
"error": {
    "code": "ErrorInvalidRecipients",
    "message": "At least one recipient is not valid., A message can't be sent because it contains no recipients."
}

}

I am trying this from postman. Same was working fine two days before. Can there be any permission issue which admin might have removed? But I am calling this API through delegated access and access token has scopes – IMAP.AccessAsUser.All Mail.Read Mail.Read.Shared Mail.ReadBasic Mail.ReadBasic.Shared Mail.ReadWrite.Shared Mail.Send.Shared profile User.Read openid email

Can someone help what could be the issue?

>Solution :

You are using wrong endpoint for sending a draft. Use the id from the previous response in the following request

POST https://graph.microsoft.com/v1.0/users/{user_id}/messages/{message_id}/send
POST https://graph.microsoft.com/v1.0/me/messages/{message_id}/send

The endpoint you were using

POST https://graph.microsoft.com/v1.0/users/{user_id}/sendMail

sends a message specified in the body and it can be used for sending a draft.