Imports System.Web.Mail
Private Sub BtnEnviar_Click(ByVal sender As System.Object _
, ByVal e As System.EventArgs) _
Handles BtnEnviar.Click
Dim mmMail As New MailMessage
Dim objSmtpServer As SmtpMail
mmMail.From = "elnapster@solocodigo.com"
mmMail.To = "elotro@domain.es"
mmMail.Subject = "Asunto"
mmMail.Body = "Cuerpo del Mensaje"
Dim oAttachment As MailAttachment = New MailAttachment("C:\prueba.txt")
mmMail.Attachments.Add(oAttachment)
objSmtpServer.SmtpServer = "smtp..."
Try
objSmtpServer.Send(mmMail)
Catch ex As Exception
MessageBox.Show("Error en envió:" & vbCrLf & ex.Message)
End Try
End Sub