package smtpd import ( "errors" "net/smtp" "strings" ) func ExampleServer() { var server *Server // No-op server. Accepts and discards server = &Server{} server.ListenAndServe() // Relay server. Accepts only from single IP address and forwards using the Gmail smtp server = &Server{ Addr: "0.0.0.0:10025", HeloChecker: func(peer Peer) error { if !strings.HasPrefix(peer.Addr.String(), "42.42.42.42:") { return errors.New("Denied") } return nil }, Handler: func(peer Peer, env Envelope) error { return smtp.SendMail( "smtp.gmail.com:587", smtp.PlainAuth( "", "username@gmail.com", "password", "smtp.gmail.com", ), env.Sender, env.Recipients, env.Data, ) }, } server.ListenAndServe() }