Simple Golang SMTP relay/proxy server

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

Bernhard Froehlich af1902f39f Bump version to 1.2.0 6 年之前
LICENSE c707438ae8 Update MIT license template 6 年之前
README.md ade7cbca36 Rename to smtprelay 6 年之前
auth.go b9d1663a18 Fixes for new authentication code 6 年之前
config.go 92be537b25 Bump version to 1.2.0 6 年之前
go.mod ade7cbca36 Rename to smtprelay 6 年之前
go.sum 76a04a2001 Authentication checker converted to store passwords as bcrypt hashes 6 年之前
main.go b9d1663a18 Fixes for new authentication code 6 年之前
smtp.go 3a96014c70 Revert package renaming 6 年之前
smtprelay.ini ade7cbca36 Rename to smtprelay 6 年之前

README.md

smtprelay

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 to GMail without giving away my GMail 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 (GMail, MailGun or any other SMTP server)
  • Small codebase
  • IPv6 support