📬 discord-smtp-relay

A tiny Go SMTP server that turns your incoming emails into fancy Discord embeds...Because plain text is so last decade. 🎉

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🚀 Features

• SMTP listener on 0.0.0.0:1025 (or whatever you choose)
• Discord embeds out of the box (no more wall-of-text “content” messages)
• Env-driven config — perfect for PM2 or Docker
• Basic auth support (SMTP AUTH PLAIN)

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🛠️ Getting Started

Prerequisites

• Go 1.15+ (modules enabled)
• A Discord Incoming Webhook URL
• Common sense

Clone & Build

git clone https://github.com/justinnamilee/discord-smtp-relay.git
cd discord-smtp-relay
go build -o discord-smtp-relay main.go

# ...

Configuration

Set these environment variables before 🚀 launch:

Variable	Required	Default	Description
WEBHOOK	✅	—	Your Discord incoming webhook URL
TEMPLATE	✅	—	Path to your JSON embed template
USERNAME	❌	discord	SMTP AUTH username (AUTH PLAIN only)
PASSWORD	❌	discord	SMTP AUTH password (AUTH PLAIN only)
ANONYMOUS	❌	false	Enable anonymous login, disable SMTP AUTH
HOST	❌	0.0.0.0	Listen interface
PORT	❌	1025	Listen port
DOMAIN	❌	localhost	EHLO/HELO domain
READ	❌	10	Read timeout (seconds)
WRITE	❌	10	Write timeout (seconds)
SIZE	❌	1024	Max message size (KB)

Run it!

# ...

env \
  WEBHOOK="https://discord.com/api/webhooks/..." \
  TEMPLATE="etc/template.example.json" \
  ./discord-smtp-relay

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🔧 PM2 Installation or Docker Usage

PM2 Installation

# ...assuming you built in last step

cp ecosystem.config.example.js ecosystem.config.js
# edit the ecosystem file as desired (set WEBHOOK, TEMPLATE)
pm2 start ecosystem.config.js
pm2 save

Docker Usage

No need to download the repo or anything!

wget 'https://raw.githubusercontent.com/justinnamilee/discord-smtp-relay/refs/heads/main/compose.example.yml' -O compose.yml
# edit the compose file as desired (set WEBHOOK, TEMPLATE)
docker compose up -d

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📤 Send an Email

Use your favorite SMTP client, or good old telnet:

$ telnet localhost 1025

EHLO localhost
AUTH PLAIN AGRpc2NvcmQAZGlzY29yZA==
MAIL FROM:<[email protected]>
RCPT TO:<[email protected]>
DATA
From: Your Pretty Name Here
To: Bots Pretty Name Here
Subject: Testing 1, 2, 3
Date: Tue, 24 Jun 2025 21:37:13 +0000

Hello Discord! This is an embedded email.
.

Watch your Discord channel light up with a nice embed instead of a boring text dump. ✨

Also, please, PLEASE make sure you update the default credentials. To generate a new AUTH PLAIN line for testing, use:

printf '\0username\0password' | base64

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🧩 Template Example

This is the file that's at etc/template.example.json, the rest of that directory is in .gitignore so add as many new ones as you want... For more details on this please see text/template and Discord Embeds. Feel free to submit ideas for new fields to support or new default templates to provide via issues or PR or w/e people normally do.

Click to expand

{
  "embeds": [
    {
      "title": "📨 {{ .Subject }}",
      "description": {{ printf "%q" .Body }},
      "color": 5814783,
      "fields": [
        {
          "name": "From",
          "value": {{ printf "%q" .From }},
          "inline": true
        },
        {
          "name": "To",
          "value": {{ printf "%q" .To }},
          "inline": true
        },
        {
          "name": "Sent",
          "value": {{ printf "%q" .Date }},
          "inline": false
        }
      ],
      "footer": {
        "text": "Received on {{ .DateGet }}"
      }
    }
  ]
}

The fields supported right now are:

• Subject
• From
• To
• Date (generated from SMTP sender)
• DateGet (generated when we get the message)

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📄 License

This project is licensed under the MIT License – see LICENSE for details.

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Pro tip #1: Markdown in embeds is supported!

Pro tip #2: Pull requests, feature requests, and emoji suggestions are very welcome. 🎈

Pro tip #3: Chew your food before swallowing.

Pro tip #4: If you use PM2, there's an example ecosystem.config.js file for you.