Deno Mailer

A lightweight SMTP client for Deno. Built with native APIs, zero dependencies, simple setup.

Table of Contents

• Installation
• Quick Start
• Configuration
  • SMTP Settings
  • Authentication
  • TLS/SSL Options
• Basic Usage
  • Simple Text Email
  • HTML Email
  • Mixed Content
  • Multiple Recipients
  • Advanced Recipient Formats
• Advanced Features
  • File Attachments
  • Embedded Images
  • Calendar Invitations
  • Custom Headers
• API Reference
  • Main API
  • Configuration Options
  • Message Properties
  • Error Handling
• Examples
  • Gmail SMTP
  • Outlook SMTP
  • Custom SMTP Server
• Troubleshooting
  • Common Issues
  • Debug Mode
• Contributing
• License

Installation

deno install @neabyte/deno-mailer

Quick Start

import mailer from '@neabyte/deno-mailer'

const transporter = mailer.transporter({
  host: 'smtp.domain.com',
  port: 587,
  secure: false,
  auth: {
    user: '[email protected]',
    pass: 'password'
  }
})

await transporter.send({
  from: '"John Doe" <[email protected]>',
  to: '[email protected]',
  subject: 'Test Email',
  text: 'This is a test email',
  html: '<b>This is a test email</b>'
})

Configuration

SMTP Settings

const config = {
  host: 'smtp.gmail.com', // SMTP server hostname
  port: 587, // SMTP server port
  secure: false, // Use TLS (true for port 465, false for 587)
  auth: {
    user: '[email protected]',
    pass: 'your-app-password'
  }
}

Authentication

Deno-Mailer supports both LOGIN and PLAIN authentication methods:

// Basic authentication
auth: {
  user: 'username',
  pass: 'password'
}

// No authentication (for local SMTP servers)
// Simply omit the auth property

TLS/SSL Options

// Port 587 with STARTTLS (recommended)
{
  host: 'smtp.gmail.com',
  port: 587,
  secure: false  // Will upgrade to TLS via STARTTLS
}

// Port 465 with direct TLS
{
  host: 'smtp.gmail.com',
  port: 465,
  secure: true   // Direct TLS connection
}

Basic Usage

Simple Text Email

await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Hello World',
  text: 'This is a plain text email'
})

HTML Email

await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'HTML Email',
  html: '<h1>Hello!</h1><p>This is an <strong>HTML</strong> email.</p>'
})

Mixed Content

await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Mixed Content',
  text: 'This is the plain text version',
  html: '<h1>This is the HTML version</h1>'
})

Multiple Recipients

await transporter.send({
  from: '[email protected]',
  to: ['[email protected]', '[email protected]'],
  cc: '[email protected]',
  bcc: '[email protected]',
  replyTo: '[email protected]',
  subject: 'Email to Multiple Recipients',
  text: 'This email goes to multiple people'
})

Advanced Recipient Formats

// Mixed recipient formats
await transporter.send({
  from: { name: 'John Doe', address: '[email protected]' },
  to: [
    '[email protected]',
    { name: 'Jane Smith', address: '[email protected]' },
    '"Display Name" <[email protected]>'
  ],
  cc: [
    '[email protected]',
    { name: 'Team Lead', address: '[email protected]' }
  ],
  bcc: '[email protected]',
  replyTo: { name: 'Support Team', address: '[email protected]' },
  subject: 'Advanced Recipient Formats',
  text: 'Supports various recipient formats'
})

Advanced Features

File Attachments

// Single attachment
await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Email with Attachment',
  text: 'Check the attached file',
  attachments: [{
    filename: 'document.pdf',
    content: fileContent, // Uint8Array or base64 string
    contentType: 'application/pdf',
    encoding: 'base64' // 'base64', '7bit', or 'quoted-printable'
  }]
})

// Multiple attachments with different encodings
await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Multiple Attachments',
  text: 'Check the attached files',
  attachments: [
    {
      filename: 'document.pdf',
      content: pdfData,
      contentType: 'application/pdf',
      encoding: 'base64'
    },
    {
      filename: 'image.jpg',
      content: imgData,
      contentType: 'image/jpeg',
      encoding: 'base64'
    },
    {
      filename: 'readme.txt',
      content: 'Plain text content',
      contentType: 'text/plain',
      encoding: '7bit'
    }
  ]
})

Embedded Images

await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Email with Image',
  html: '<h1>Hello!</h1><img src="cid:logo">',
  embeddedImages: [{
    filename: 'logo.png',
    content: imageContent,
    contentType: 'image/png',
    cid: '<[email protected]>',
    disposition: 'inline' // 'inline' or 'attachment'
  }]
})

Calendar Invitations

// Basic calendar event
await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Meeting Invitation',
  text: 'You are invited to a meeting',
  calendarEvent: {
    uid: 'meeting-123',
    summary: 'Team Meeting',
    description: 'Weekly team sync',
    location: 'Conference Room A',
    startTime: '2024-01-15T10:00:00Z',
    endTime: '2024-01-15T11:00:00Z',
    organizer: '[email protected]',
    attendees: ['[email protected]', '[email protected]']
  }
})

// Complete calendar event with all options
await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Important Meeting',
  text: 'Please attend this important meeting',
  html: '<h1>Important Meeting</h1><p>Please attend this meeting.</p>',
  calendarEvent: {
    uid: 'important-meeting-456',
    summary: 'Quarterly Review',
    description: 'Q4 performance review and planning for next quarter',
    location: 'Main Conference Room, Building A',
    startTime: '2024-01-20T14:00:00Z',
    endTime: '2024-01-20T16:00:00Z',
    organizer: '[email protected]',
    attendees: [
      '[email protected]',
      '[email protected]',
      '[email protected]'
    ],
    status: 'CONFIRMED'
  }
})

Custom Headers

await transporter.send({
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Custom Headers',
  text: 'Email with custom headers',
  headers: {
    'X-Priority': '1',
    'X-Custom-Header': 'Custom Value'
  }
})

API Reference

Main API

Method	Description	Parameters	Returns
mailer.transporter(config)	Creates email transporter	SmtpConnectionConfig	EmailSender
transporter.send(message)	Sends email message	EmailMessage	Promise<void>

Configuration Options

Option	Type	Required	Description	Example
host	string	✅	SMTP server hostname	'smtp.gmail.com'
port	number	✅	SMTP server port	587, 465, 25
secure	boolean	❌	Use TLS connection	true (port 465), false (port 587)
auth.user	string	❌	SMTP username	'[email protected]'
auth.pass	string	❌	SMTP password	'your-password'

Message Properties

Property	Type	Required	Description	Examples
from	string/object	✅	Sender email address	'[email protected]', {name: 'John', address: '[email protected]'}
to	string/array	✅	Recipient email address(es)	'[email protected]', ['[email protected]', '[email protected]']
subject	string	✅	Email subject line	'Hello World'
text	string	❌	Plain text content	'This is plain text'
html	string	❌	HTML content	'<h1>Hello</h1>'
cc	string/array	❌	Carbon copy recipients	'[email protected]'
bcc	string/array	❌	Blind carbon copy recipients	'[email protected]'
replyTo	string/object	❌	Reply-to address	'[email protected]'
attachments	array	❌	File attachments	[{filename: 'file.pdf', content: data}]
embeddedImages	array	❌	Embedded images	[{filename: 'img.png', content: data, cid: '<[email protected]>'}]
calendarEvent	object	❌	Calendar invitation	{uid: 'event-123', summary: 'Meeting', startTime: '2024-01-01T10:00:00Z'}
headers	object	❌	Custom email headers	{'X-Priority': '1'}

Error Handling

try {
  await transporter.send(message)
} catch (error) {
  console.error('Email failed:', error.message)
  // Handle specific error types
  if (error.message.includes('authentication')) {
    // Handle auth errors
  } else if (error.message.includes('connection')) {
    // Handle connection errors
  }
}

Examples

Gmail SMTP

const transporter = mailer.transporter({
  host: 'smtp.gmail.com',
  port: 587,
  secure: false,
  auth: {
    user: '[email protected]',
    pass: 'your-app-password' // Use App Password, not regular password
  }
})

Outlook SMTP

const transporter = mailer.transporter({
  host: 'smtp-mail.outlook.com',
  port: 587,
  secure: false,
  auth: {
    user: '[email protected]',
    pass: 'your-password'
  }
})

Custom SMTP Server

const transporter = mailer.transporter({
  host: 'mail.yourcompany.com',
  port: 587,
  secure: false,
  auth: {
    user: '[email protected]',
    pass: 'your-password'
  }
})

Troubleshooting

Common Issues

Authentication Failed

• Verify username/password are correct
• For Gmail, use App Passwords instead of regular passwords
• Check if 2FA is enabled and use App Password

Connection Timeout

• Verify SMTP server hostname and port
• Check firewall settings
• Try different ports (587, 465, 25)

TLS Errors

• Ensure secure: false for port 587 (STARTTLS)
• Use secure: true for port 465 (direct TLS)
• Check server TLS certificate

Debug Mode

// Add error logging
try {
  await transporter.send(message)
  console.log('Email sent successfully')
} catch (error) {
  console.error('SMTP Error:', error.message)
}

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT license. See the LICENSE file for more info.