Dim ObjMail As New System.Net.Mail.MailMessage()
Dim ObjMailFrom As New System.Net.Mail.MailAddress("Email del mittente", "Nome del mittente")
ObjMail.From = ObjMailFrom
ObjMail.To.Add("email di destinazione")
ObjMail.Subject = "Oggetto della email"
ObjMail.Body = "Messaggio"
Dim OutSmtp As New System.Net.Mail.SmtpClient("server smtp", 25)
OutSmtp.UseDefaultCredentials = True
OutSmtp.DeliveryMethod = Net.Mail.SmtpDeliveryMethod.Network

'Eventuale allegato
ObjMail.Attachments.Add(New System.Net.Mail.Attachment(Server.MapPath("nome del file")))

OutSmtp.Send(ObjMail)