Simple Golang SMTP relay/proxy server

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

Bernhard Froehlich ab9334249f ci: Add missing permissions for release workflow 1 年之前
.github 6919131eec ci: Add missing permissions for release workflow 1 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 813bd9ebe7 Support .env files if it exists 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 5b5f738410 make possible #91. 2 年之前
config_test.go 441a53cfd9 Fix code formatting with gofmt -s 4 年之前
go.mod ae0f9ba0b6 Update go dependencies 1 年之前
go.sum ae0f9ba0b6 Update go dependencies 1 年之前
logger.go 441a53cfd9 Fix code formatting with gofmt -s 4 年之前
main.go 6c1bffcff0 Merge branch 'decke:master' into master 2 年之前
main_test.go 7f34fcbc99 gofmt: Fix formatting 4 年之前
remotes.go ee8a5dd989 Fix code formatting 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 2590282fa4 Add strict_sender to smtprelay.ini 2 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

  • Simple configuration with ini file .env file or environment variables
  • 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