smtp/relay.go

   1 // mailpopbox
   2 // Copyright 2020 Blue Static <https://www.bluestatic.org>
   3 // This program is free software licensed under the GNU General Public License,
   4 // version 3.0. The full text of the license can be found in LICENSE.txt.
   5 // SPDX-License-Identifier: GPL-3.0-only
   6
   7 package smtp
   8
   9 import (
  10         "net"
  11         "net/smtp"
  12
  13         "github.com/uber-go/zap"
  14 )
  15
  16 func RelayMessage(env Envelope, log zap.Logger) {
  17         for _, rcptTo := range env.RcptTo {
  18                 domain := DomainForAddress(rcptTo)
  19                 mx, err := net.LookupMX(domain)
  20                 if err != nil || len(mx) < 1 {
  21                         log.Error("failed to lookup MX records",
  22                                 zap.String("address", rcptTo.Address),
  23                                 zap.Error(err))
  24                         deliverRelayFailure(env, err)
  25                         return
  26                 }
  27
  28                 to := []string{rcptTo.Address}
  29                 from := env.MailFrom.Address
  30                 host := mx[0].Host + ":25"
  31
  32                 log.Info("relay message",
  33                         zap.String("to", to[0]),
  34                         zap.String("from", from),
  35                         zap.String("server", host))
  36                 err = smtp.SendMail(host, nil, from, to, env.Data)
  37                 if err != nil {
  38                         log.Error("failed to relay message",
  39                                 zap.String("address", rcptTo.Address),
  40                                 zap.Error(err))
  41                         deliverRelayFailure(env, err)
  42                         return
  43                 }
  44         }
  45 }
  46
  47 func deliverRelayFailure(env Envelope, err error) {
  48         // TODO: constructo a delivery status notification
  49 }