funcmain() { // Set up authentication information. auth := smtp.PlainAuth( "", "user@example.com", "password", "mail.example.com", ) // Connect to the server, authenticate, set the sender and recipient, // and send the email all in one step. err := smtp.SendMail( "mail.example.com:25", auth, "sender@example.org", []string{"recipient@example.net"}, []byte("This is the email body."), ) if err != nil { log.Fatal(err) } }