Relsend

A modern CLI for sending emails with TypeScript template support, built with Bun. Supports multiple email providers including Nodemailer (SMTP) and Resend. Optimized for Bun users.

Installation

bun add -D @reliverse/relsend
# or globally: bun add -g @reliverse/relsend

Usage

bun relsend <command> [options]
# or globally: relsend <command> [options]

Quick Start

# 1. Setup configuration
cp .env.example .env
# Edit .env with your email settings

# 2. Send your first email
# Using Nodemailer (default)
bun relsend send --to "[email protected]" --subject "Hello" --text "This is a test email" --from 1

# Using Resend
bun relsend send --provider resend --apiKey re_123456789 --to "[email protected]" --subject "Hello" --text "This is a test email"

Quick Setup

1. Choose Your Email Provider

Relsend supports two email providers:

Nodemailer (default) - For SMTP servers like Gmail, Outlook, etc.
Resend - Modern email API with excellent deliverability

2. Configure Environment Variables

Option A: Nodemailer (SMTP)

First, set up your Gmail App Password at https://myaccount.google.com/apppasswords, then configure Relsend:

# Relsend Configuration
# Copy the .env.example file to .env and fill in your values

# SMTP Server Configuration
RELSEND_HOST=smtp.gmail.com
# RELSEND_PROVIDER=nodemailer
# (465 & secure=true; 587 & secure=false)
RELSEND_PORT=587
RELSEND_SECURE=false
RELSEND_AUTH_TYPE=password

# [Auth Type]: Authentication
[email protected]
RELSEND_USER_PASS_1=your-16-char-app-password
# [email protected]
# RELSEND_USER_PASS_2=app-password-2

# [Auth Type]: OAuth2 Configuration
# RELSEND_AUTH_TYPE=oauth2
# RELSEND_CLIENT_ID=your-oauth-client-id
# RELSEND_CLIENT_SECRET=your-oauth-client-secret
# RELSEND_REFRESH_TOKEN=your-oauth-refresh-token

Alternative: Use the config command to set values programmatically (host/port/secure/auth only — accounts are set via env):

bun relsend config set host=smtp.gmail.com port=587 secure=false
bun relsend config get  # Verify configuration

Option B: Resend

Get your API key from https://resend.com/api-keys, then configure:

# Edit .env with your Resend settings
# RELSEND_PROVIDER=resend
# RELSEND_API_KEY=re_123456789
# (use RELSEND_USER_NAME_<index> and select via --from)

3. List Available Templates

# See all available templates
bun relsend template list

# Get template details and required variables
bun relsend template info welcome
bun relsend template info notification
bun relsend template info newsletter
bun relsend template info my-email

Usage Examples

Send Welcome Email

# Using Nodemailer (default)
bun relsend send --template welcome --templateData '{"userName":"John","companyName":"Acme Corp","userEmail":"[email protected]","userRole":"Developer","startDate":"2025-01-15","supportEmail":"[email protected]"}' --to "[email protected]" --from random

# Using Resend
bun relsend send --provider resend --template welcome --templateData '{"userName":"John","companyName":"Acme Corp","userEmail":"[email protected]","userRole":"Developer","startDate":"2025-01-15","supportEmail":"[email protected]"}' --to "[email protected]" --from 1

Send Notification Email

# Using Nodemailer
bun relsend send --template notification --templateData '{"notificationType":"Alert","title":"System Maintenance","recipientName":"John","message":"Scheduled maintenance tonight at 2 AM","actionRequired":true,"actionText":"Please save your work","deadline":"Tonight at 11 PM","link":"https://status.acme.com","senderName":"IT Team","senderTitle":"System Administrator","companyName":"Acme Corp","priorityColor":"#dc3545"}' --to "[email protected]" --from 2

# Using Resend
bun relsend send --provider resend --template notification --templateData '{"notificationType":"Alert","title":"System Maintenance","recipientName":"John","message":"Scheduled maintenance tonight at 2 AM","actionRequired":true,"actionText":"Please save your work","deadline":"Tonight at 11 PM","link":"https://status.acme.com","senderName":"IT Team","senderTitle":"System Administrator","companyName":"Acme Corp","priorityColor":"#dc3545"}' --to "[email protected]" --from 2

Send Email with Tailwind CSS

# Use react-email Tailwind (default - v3 mode) with Nodemailer
bun relsend send --template my-email --tailwind v3 --templateData '{"userName":"John","companyName":"Acme Corp","ctaUrl":"https://acme.com","ctaText":"Get Started"}' --to "[email protected]"

# Use react-email Tailwind with Resend
bun relsend send --provider resend --template my-email --tailwind v3 --templateData '{"userName":"John","companyName":"Acme Corp","ctaUrl":"https://acme.com","ctaText":"Get Started"}' --to "[email protected]"

# Use manual CSS compilation (v4 mode)
bun relsend send --template my-email --tailwind v4 --templateData '{"userName":"John","companyName":"Acme Corp"}' --to "[email protected]"

# Use no CSS (off mode - for custom CSS files)
bun relsend send --template my-email --tailwind off --templateData '{"userName":"John","companyName":"Acme Corp"}' --to "[email protected]"

Relsend Newsletter Templates

Relsend includes built-in newsletter templates for onboarding and advanced features:

# Send onboarding email (randomly selects between onboard and advanced-details)
bun relsend send --template newsletter --to "[email protected]" --from 1

# Using Resend
bun relsend send --provider resend --template newsletter --to "[email protected]" --from 1

Template Details

The newsletter template includes two variants:

Onboard Email: Welcome new users with quick start guide, key features, and setup instructions
Advanced Details Email: Comprehensive technical guide covering architecture, TypeScript templates, providers, and production best practices

Both templates feature modern design with Tailwind CSS, responsive layouts, and comprehensive Relsend documentation.

Send Simple Email (No Template)

# Using Nodemailer (default)
bun relsend send --to "[email protected]" --subject "Hello" --text "This is a test email"

# Using Resend
bun relsend send --provider resend --to "[email protected]" --subject "Hello" --text "This is a test email"

Override Configuration (Optional)

You can override any configuration from your .env file by passing flags:

# Override sender email for this specific email
bun relsend send --to "[email protected]" --from "[email protected]" --subject "Hello"

# Override provider and settings for this specific email
bun relsend send --provider resend --apiKey re_123456789 --to "[email protected]" --subject "Hello"

# Override SMTP settings for this specific email
bun relsend send --to "[email protected]" --host "smtp.outlook.com" --port 587 --user "[email protected]" --pass "outlook-password" --subject "Hello"

Environment Variables

Relsend uses the following environment variables for configuration:

Provider Selection

Variable	Description	Example
`RELSEND_PROVIDER`	Email provider	`nodemailer` or `resend`

Nodemailer (SMTP) Configuration

Variable	Description	Example
`RELSEND_HOST`	SMTP server hostname	`smtp.gmail.com`
`RELSEND_PORT`	SMTP server port	`587`
`RELSEND_SECURE`	Use SSL/TLS connection	`false`
`RELSEND_USER_NAME_<i>`	Account email for index i (1..10)	`[email protected]`
`RELSEND_USER_PASS_<i>`	Account password/app password	`your-app-password`
`RELSEND_AUTH_TYPE`	Authentication type	`password` or `oauth2`
`RELSEND_CLIENT_ID`	OAuth2 client ID	`your-oauth-client-id`
`RELSEND_CLIENT_SECRET`	OAuth2 client secret	`your-oauth-client-secret`
`RELSEND_REFRESH_TOKEN`	OAuth2 refresh token	`your-oauth-refresh-token`

Resend Configuration

Variable	Description	Example
`RELSEND_API_KEY`	Resend API key	`re_123456789`

Email Providers

Relsend supports two email providers, each with their own advantages:

Nodemailer (Default)

Best for: Traditional SMTP servers (Gmail, Outlook, custom SMTP)
Authentication: App passwords, OAuth2
Configuration: SMTP host, port, credentials
Use case: When you have existing SMTP infrastructure

Resend

Best for: Modern applications requiring high deliverability
Authentication: API key
Configuration: Simple API key setup
Use case: When you want excellent deliverability and simple setup

Provider Selection Examples

# Use Nodemailer (default)
bun relsend send --to [email protected] --subject "Hello" --text "Hello World"

# Use Resend explicitly
bun relsend send --provider resend --apiKey re_123456789 --to [email protected] --subject "Hello" --text "Hello World"

# Set default provider in .env
echo "RELSEND_PROVIDER=resend" >> .env
echo "RELSEND_API_KEY=re_123456789" >> .env

Commands

send - Send emails with templates or raw content using Nodemailer or Resend
config get|set - Manage email provider configuration (updates .env file)
template list|info - List and inspect email templates
help - Show detailed help with provider options

Tailwind CSS Integration

Relsend supports multiple Tailwind CSS modes for flexible email styling:

Tailwind Modes

v3 (default) - Uses react-email Tailwind component with inline styles
- Best for: Modern email clients with full CSS support
- Features: Automatic inline styles, email client compatibility
- Requires: @react-email/tailwind package
v4 - Uses manual CSS compilation from styles/dist/output.css
- Best for: Custom Tailwind builds and advanced configurations
- Features: Full control over CSS compilation
- Requires: Manual CSS build process
off - No CSS link (for custom CSS files)
- Best for: Custom CSS files or external stylesheets
- Features: Complete control over styling
- Requires: Manual CSS file management

Usage Example

# Default mode (react-email Tailwind)
bun relsend send --template my-email --tailwind v3 --to [email protected] --from random

# Manual CSS mode
bun relsend send --template my-email --tailwind v4 --to [email protected] --from random

# No CSS mode
bun relsend send --template my-email --tailwind off --to [email protected] --from random

Template Development

For templates using react-email Tailwind (v3 mode), use the Tailwind component:

import { Button, Head, Html, Tailwind, pixelBasedPreset } from "@react-email/components";

function MyEmail() {
  return (
    <Html>
      <Tailwind
        config={{
          presets: [pixelBasedPreset],
          theme: {
            extend: {
              colors: {
                brand: "#007291",
              },
            },
          },
        }}
      >
        <Head />
        <div className="bg-gray-50 p-8">
          <Button className="bg-brand px-6 py-3 text-white">
            Click me
          </Button>
        </div>
      </Tailwind>
    </Html>
  );
}

Why Environment Variables?

Using .env files provides several advantages:

✅ Security - Keep sensitive credentials out of command history
✅ Simplicity - No need to pass SMTP flags with every command
✅ Flexibility - Override any setting with command-line flags when needed
✅ Portability - Share configuration across different environments
✅ Bun Native - Automatic loading without additional dependencies

Features

✅ Multiple Email Providers - Nodemailer (SMTP) and Resend support
✅ Gmail Support - OAuth2 and App Password authentication via Nodemailer
✅ Resend Integration - Modern email API with excellent deliverability
✅ TypeScript Templates - Component-based email templates
✅ React Email Support - Built-in react-email components with Tailwind
✅ Tailwind CSS Integration - Multiple Tailwind modes (v3, v4, off)
✅ Environment Variables - Simple .env file configuration
✅ Template Variables - Dynamic content with {{variable}} syntax
✅ HTML + Text - Both formats supported
✅ Modern CLI - Built with Bun for speed
✅ Zero Dependencies - Uses Bun's native environment variable support
✅ Visual Feedback - Beautiful spinners for all operations
✅ Provider Flexibility - Switch between providers with --provider flag

Nerd Details

🔍 What Nodemailer Receives (Your Input)

{
  from: "[email protected]",
  to: "[email protected]", 
  subject: "Test Email",
  text: "Plain text version",
  html: "<h1>HTML version</h1>"
}

📧 What Nodemailer Actually Sends (Raw Email)

MIME-Version: 1.0
From: [email protected]
To: [email protected]
Subject: Test Email
Date: Sun, 07 Sep 2025 18:59:05 GMT
Message-ID: <unique-id@domain>
Content-Type: multipart/alternative; boundary="----=_NextPart_000_0000_01DA1234567890"

------=_NextPart_000_0000_01DA1234567890
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit

Plain text version

------=_NextPart_000_0000_01DA1234567890
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: 7bit

<h1>HTML version</h1>

------=_NextPart_000_0000_01DA1234567890--

Key Points:

MIME Multipart Structure: Nodemailer creates a structured email with multiple parts separated by boundary markers
Both Text & HTML: When provided both, it includes both versions
Email Headers: Adds standard email headers (Date, Message-ID, Content-Type, etc.)
Encoding: Handles character encoding and transfer encoding
Fallback Support: Email clients can choose which version to display

Relsend CLI's Preview Shows:

The content parts that will be sent (text and HTML separately)
Not the raw MIME structure (that's nodemailer's job)
React components rendered to HTML before sending
Exactly what the recipient will see in their email client

How Email Clients Handle It:

Modern clients (Gmail, Outlook, Apple Mail): Display the HTML version
Text-only clients (some mobile apps, accessibility tools): Show the plain text
"Show Original" in Gmail: Shows the raw MIME structure
Fallback behavior: If HTML fails to load, falls back to plain text

Contributors

We welcome contributions! 👋

TODO:

Add Panda CSS support

Name		Name	Last commit message	Last commit date
Latest commit History 7 Commits
.cursor/rules		.cursor/rules
.vscode		.vscode
emails		emails
example		example
src		src
styles		styles
.env.example		.env.example
.gitignore		.gitignore
LICENSE		LICENSE
README.md		README.md
biome.json		biome.json
bun.lock		bun.lock
package.json		package.json
reliverse.ts		reliverse.ts
reltypes.ts		reltypes.ts
tailwind.config.ts		tailwind.config.ts
tsconfig.json		tsconfig.json

License

reliverse/relsend

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Relsend

Installation

Usage

Quick Start

Quick Setup

1. Choose Your Email Provider

2. Configure Environment Variables

Option A: Nodemailer (SMTP)

Option B: Resend

3. List Available Templates

Usage Examples

Send Welcome Email

Send Notification Email

Send Email with Tailwind CSS

Relsend Newsletter Templates

Template Details

Send Simple Email (No Template)

Override Configuration (Optional)

Environment Variables

Provider Selection

Nodemailer (SMTP) Configuration

Resend Configuration

Email Providers

Nodemailer (Default)

Resend

Provider Selection Examples

Commands

Tailwind CSS Integration

Tailwind Modes

Usage Example

Template Development

Why Environment Variables?

Features

Nerd Details

🔍 What Nodemailer Receives (Your Input)

📧 What Nodemailer Actually Sends (Raw Email)

Key Points:

Relsend CLI's Preview Shows:

How Email Clients Handle It:

Contributors

License

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