i want other user send me email using my application that made by Visual studio.

See more:

email

I get this error when debug..

An unhandled exception of type 'System.FormatException' occurred in System.dll

Additional information: The specified string is not in the form required for an e-mail address.

And this is my code..

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Dim smtpServer As New SmtpClient()
        Dim mail As New MailMessage()
        smtpServer.Credentials = New Net.NetworkCredential(TextBox15.Text, TextBox16.Text)
        smtpServer.Port = 587
        smtpServer.Host = "smtp.gmail.com"
        smtpServer.EnableSsl = True
        mail = New MailMessage()
        mail.From = New MailAddress(TextBox18.Text)
        mail.To.Add(TextBox17.Text)
        mail.Subject = TextBox19.Text
        mail.Body = TextBox20.Text
        smtpServer.Send(mail)
        MsgBox("Mail Sent!", MsgBoxStyle.OkOnly, "Sent")
    End Sub
End Class