Oauth 2.0 SMTP send email with EASendEmail VB - vb.net

Question

Following the changes, I try to connect and send mails via EAGetMail/EASendMail.
The connection is good, I have good access to the token and also to my mailbox.
However, when I want to send an email via "smtp.office365.com" I get an error: 535 5.7.3 Authentication unsuccessful.
I do not understand where the error can come from, I take the same token as when connecting to the mailbox.
Below is just the code to send emails, I have a token and it works perfectly to connect to my email
If someone has a project that works with smtp and Oauth 2.0 (without using a browser)...
Module Module1
Sub Main(ByVal args As String())
Try
RetrieveEmail()
Catch ep As Exception
Console.WriteLine(ep.ToString())
End Try
Console.ReadKey()
End Sub
Function _generateFileName(ByVal sequence As Integer) As String
Dim currentDateTime As DateTime = DateTime.Now
Return String.Format("{0}-{1:000}-{2:000}.eml",
currentDateTime.ToString("yyyyMMddHHmmss", New CultureInfo("en-US")),
currentDateTime.Millisecond,
sequence)
End Function
Function _postString(ByVal uri As String, ByVal requestData As String) As String
Dim httpRequest As HttpWebRequest = TryCast(WebRequest.Create(uri), HttpWebRequest)
httpRequest.Method = "POST"
httpRequest.ContentType = "application/x-www-form-urlencoded"
Using requestStream As Stream = httpRequest.GetRequestStream()
Dim requestBuffer As Byte() = Encoding.UTF8.GetBytes(requestData)
requestStream.Write(requestBuffer, 0, requestBuffer.Length)
requestStream.Close()
End Using
Try
Dim httpResponse As HttpWebResponse = TryCast(httpRequest.GetResponse(), HttpWebResponse)
Using reader As New StreamReader(httpResponse.GetResponseStream())
Dim responseText = reader.ReadToEnd()
Return responseText
End Using
Catch ex As WebException
If ex.Status = WebExceptionStatus.ProtocolError Then
Dim response = TryCast(ex.Response, HttpWebResponse)
If response IsNot Nothing Then
Console.WriteLine("HTTP: " & response.StatusCode)
' reads response body
Using reader As StreamReader = New StreamReader(response.GetResponseStream())
Dim responseText As String = reader.ReadToEnd()
Console.WriteLine(responseText)
End Using
End If
End If
Throw ex
End Try
End Function
Public Sub RetrieveEmail()
Try
Dim client_id As String = "XXXXXXXXXXXXXXXXXXXX"
Dim client_secret As String = "XXXXXXXXXXXXXXXXXXXXXXXXX"
' If your application is not created by Office365 administrator,
' please use Office365 directory tenant id, you should ask Offic365 administrator to send it to you.
' Office365 administrator can query tenant id in https://portal.azure.com/ - Azure Active Directory.
Dim tenant As String = "XXXXXXXXXXXXXXXXXX"
Dim requestData As String = String.Format("client_id={0}&client_secret={1}&scope=https://outlook.office365.com/.default&grant_type=client_credentials",
client_id, client_secret)
Dim tokenUri As String = String.Format("https://login.microsoftonline.com/{0}/oauth2/v2.0/token", tenant)
Dim responseText As String = _postString(tokenUri, requestData)
Dim parser As EASendMail.OAuthResponseParser = New EASendMail.OAuthResponseParser()
parser.Load(responseText)
Dim officeUser As String = "tma#XXXX.fr"
Dim oServerSend As SmtpServer = New SmtpServer("smtp.office365.com")
oServerSend.ConnectType = SmtpConnectType.ConnectSSLAuto
oServerSend.Port = 587
oServerSend.AuthType = SmtpAuthType.XOAUTH2
oServerSend.User = officeUser
oServerSend.Password = parser.AccessToken
Dim oMailSend As SmtpMail = New SmtpMail("TryIt")
oMailSend.From = "tma#XXX.fr"
' Please change recipient address to yours for test
oMailSend.[To] = "XXXXXXXXXXX"
oMailSend.Subject = "test email from Hotmail account with OAUTH 2"
oMailSend.TextBody = "this is a test email sent from VB.NET project with Hotmail."
Console.WriteLine("start to send email using OAUTH 2.0 ...")
Dim oSmtp As SmtpClient = New SmtpClient()
oSmtp.SendMail(oServerSend, oMailSend)
' Quit and expunge emails marked as deleted from server.
Console.WriteLine("Completed!")
Catch ep As Exception
Console.WriteLine(ep.ToString())
End Try
End Sub
End Module