80x86/smtp-brd repository overview

smtp bridge for apps which want to send email in the traditional SMTP way but actully goes to the WEB API

currently support mailgun and sendgrid

⁠for latest updated document, please see https://github.com/ttys3/smtp-brd⁠

⁠smtp-brd

⁠description

the main goal of this project is setup as a side container

for remark42 comment system to send email via WEB API

but the usage of it is not limited to this

⁠available providers

mailgun
sendgrid

⁠run with podman

sudo podman run -d --name smtpbrd -p 2525:2525 \
-e BRD_PROVIDER=sendgrid \
-e BRD_SENDGRID_API_KEY='SG-KEY-HERE' \
80x86/smtp-brd:latest

⁠run with Docker

sudo docker run -d --name smtpbrd -p 2525:2525 \
-e BRD_PROVIDER=sendgrid \
-e BRD_SENDGRID_API_KEY='SG-KEY-HERE' \
80x86/smtp-brd:latest

⁠config

there are 3 ways to config

• the config.toml file
• environment variables
• command line interface parameters

take mailgun.api_key for example:

config.toml

# Mailgun
[mailgun]
api_key = ""

the equal environment variable is BRD_MAINGUN_API_KEY be aware here we introduced a prefix BRD_ to avoid conflict

the equal cli param is --mailgun.api_key

run smtp-brd --help for full config options

the environment variables is recommend way for running in container.

⁠available config env vars and their default value

⁠general env vars

    BRD_ADDR="0.0.0.0"
    BRD_PORT="2525"
    BRD_TLS=false
    BRD_CERT="/etc/brd/ssl/ssl.crt"
    BRD_KEY="/etc/brd/ssl/ssl.key"
    BRD_DEBUG=false
    BRD_USER=""
    BRD_SECRET=""
    BRD_PROVIDER="mailgun"

⁠system related base env vars

TZ=Asia/Hong_Kong
PUID=1000
PGID=1000

you can run the container in your own timezone, just to specific the env var, for example:

TZ=America/Los_Angeles

⁠provider related env vars

mailgun provider

    BRD_MAILGUN_API_KEY=""
    BRD_MAILGUN_DOMAIN=""
    BRD_MAILGUN_TIMEOUT=10

sendgrid provider

    BRD_SENDGRID_API_KEY=""
    BRD_SENDGRID_TIMEOUT=10

⁠TODO

• more tests

⁠TLS

default certificate stores under /etc/brd/ssl

however in container, you can map it to any path as you like

just set the correct value for BRD_CERT and BRD_KEY

⁠FAQ

1. smtp.plainAuth failed: unencrypted connection

   You need either to setup TLS on your SMTP server, use localhost as a relay or disable authentication. the answer come from
   this issue⁠

   The error is because the Go SMTP package doesn't allow authentication without encryption. From https://godoc.org/net/smtp#PlainAuth⁠

   PlainAuth will only send the credentials if the connection is using TLS or is connected to localhost. Otherwise authentication will fail with an error, without sending the credentials.

2. got x509: certificate signed by unknown authority error while TLS enabled

   The error is because the Go net/smtp client tls.Config.InsecureSkipVerify is enforced to true

   if TLS enabled, be sure your have valid certificate

   self-signed cert is not allowed by golang smtp client

⁠thanks

mail parser this project use github.com/veqryn/go-email/email to parse email
repo⁠

minimal SMTP server use github.com/mhale/smtpd repo⁠,
which seems based on the work of Brad Fitzpatrick's go-smtpd⁠

flags parser github.com/spf13/pflag repo⁠

config manager github.com/spf13/viper repo⁠

logger go.uber.org/zap repo⁠