How to send an email without involving outlook using SMTP server in VB.NET

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VB15

Hi,
Good day.
I have a project in VB.net, its a windows form application.
All is good, but i could not send email without involving outlook. System gives the following error ....

"

The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication Required. For more information, go to

"

Can anyone highlight what kind of mistake i am doing.

The code that i wrote is ............

What I have tried:

Public Sub Send_Email_SMTP()
       Try
           Dim SmtpServer As New SmtpClient()
           SmtpServer.UseDefaultCredentials = False
           SmtpServer.EnableSsl = True
           Dim mail As New MailMessage()
           SmtpServer.Credentials = New _
           Net.NetworkCredential("from@gmail.com", "password")
           SmtpServer.Port = 587
           SmtpServer.Host = "smtp.gmail.com"
           mail = New MailMessage()
           mail.From = New MailAddress("from@gmail.com")
           mail.To.Add("to@gmail.com")
           mail.Subject = "My Email Subject"
           mail.Body = "My Email Body"
           SmtpServer.Send(mail)
           MsgBox("Email has been sent")
       Catch ex As SmtpException
           MessageBox.Show(ex.Message, "Send_Email_SMTP", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
       End Try
End Sub