Simple Golang SMTP relay/proxy server

Topics
#golang #proxy-server #smtp-server #smtp-relay #ssl #load-balancer

Bernhard Froehlich fe32180fbc Remove i386 from release builds 3 年之前
.github c21c13cc7a Remove i386 from release builds 3 年之前
cmd 009ae8f73a hasher: Check number of arguments 4 年之前
LICENSE c707438ae8 Update MIT license template 6 年之前
README.md 1617155f1e Remove service names from readme 3 年之前
auth.go 7f34fcbc99 gofmt: Fix formatting 4 年之前
auth_test.go 7f34fcbc99 gofmt: Fix formatting 4 年之前
config.go 4221919689 Allow config to have multiple remotes. 3 年之前
config_test.go 441a53cfd9 Fix code formatting with gofmt -s 4 年之前
go.mod ce97293e33 Update Go crypto and sys dependencies 3 年之前
go.sum ce97293e33 Update Go crypto and sys dependencies 3 年之前
logger.go 441a53cfd9 Fix code formatting with gofmt -s 4 年之前
main.go b134e426d7 Propagate the error to the client if the external command fails (#40) 3 年之前
main_test.go 7f34fcbc99 gofmt: Fix formatting 4 年之前
remotes.go b7f3701502 Add missing default port for starttls and validate scheme to ensure support 3 年之前
remotes_test.go 875264837e add test coverage for scheme validation 3 年之前
smtp.go 5cd81cd7e4 smtp: gofmt main repo 3 年之前
smtprelay.ini 5e78bbe643 Improve remotes documentation in config 3 年之前

README.md

smtprelay

Go Report Card

Simple Golang based SMTP relay/proxy server that accepts mail via SMTP and forwards it directly to another SMTP server.

Why another SMTP server?

Outgoing mails are usually send via SMTP to an MTA (Mail Transfer Agent) which is one of Postfix, Exim, Sendmail or OpenSMTPD on UNIX/Linux in most cases. You really don't want to setup and maintain any of those full blown kitchensinks yourself because they are complex, fragile and hard to configure.

My use case is simple. I need to send automatically generated mails from cron via msmtp/sSMTP/dma, mails from various services and network printers via a remote SMTP server without giving away my mail credentials to each device which produces mail.

Main features

  • Supports SMTPS/TLS (465), STARTTLS (587) and unencrypted SMTP (25)
  • Checks for sender, receiver, client IP
  • Authentication support with file (LOGIN, PLAIN)
  • Enforce encryption for authentication
  • Forwards all mail to a smarthost (any SMTP server)
  • Small codebase
  • IPv6 support