Send email using Microsoft Outlook in ASP.Net using C# and VB.Net

I have found a solution but I am getting an error message. I am also confused as to what username and password i should use because this web app will not be used by me but rather various users.

This is my code in Button Click: 

 Protected Sub btnSend_Click(sender As Object, e As EventArgs) Handles btnSend.Click

        Try

        Dim mailsubject As String = txtSubject.Text
        Dim mailbody As String = txtMessage.Text
        Dim mailmsg As MailMessage = New MailMessage(txtFrom.Text, txtTo.Text)
        mailmsg.Subject = mailsubject
        mailmsg.Body = mailbody
        mailmsg.IsBodyHtml = True
        Dim smtp As SmtpClient = New SmtpClient()
        smtp.Send(mailmsg)

        Catch

        End Try




    End Sub

This is my code in my web.config file:

<system.net>
    <mailSettings>
      <smtp deliveryMethod="Network">
        <network host="smtp-mail.outlook.com" enableSsl="true" port="587" userName="*****" password="******"/>
      </smtp>
    </mailSettings>
  </system.net>

 This is my error message that i am getting:

Below is the error message that I am getting: System.Net.Mail.SmtpException: 'The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM [PR0P264CA0207.FRAP264.PROD.OUTLOOK.COM]'