Built in Koder Lang

Meet Mail

A fast, privacy-focused webmail client with OIDC authentication, JMAP proxy for modern email access, end-to-end encryption, and a clean interface designed for productive communication.

# Connect and send email via JMAP
require "koder-mail"

client = mail.connect({
  server: "https://mail.koder.dev",
  auth: "oidc",
  provider: "https://auth.koder.dev"
})

# Send encrypted email
await client.send({
  to: "team@company.com",
  subject: "Q1 Report — Confidential",
  body: "Please find the report attached.",
  attachments: ["./q1-report.pdf"],
  encrypt: true, # PGP auto-encrypt
  sign: true
})

# Search with advanced filters
results = await client.search({
  from: "ceo@company.com",
  hasAttachment: true,
  after: "2026-01-01"
})

Features

Everything you need, built from the ground up.

⚡
JMAP Protocol Support

Built on JMAP (RFC 8620/8621), the modern replacement for IMAP. Push-based sync, efficient bandwidth usage, and instant updates across all clients.

⚖
OIDC Authentication

Single sign-on with OpenID Connect. Integrate with your existing identity provider — Keycloak, Auth0, Okta, or any OIDC-compliant provider.

⚙
End-to-End Encryption

PGP and S/MIME encryption built into the web interface. Encrypt emails with one click, manage keys in-app, and auto-discover recipient keys.

☁
Smart Inbox

AI-powered email categorization, priority detection, and smart filters. Important emails surface first, newsletters and notifications are organized automatically.

🔒
Lightning-Fast Search

Full-text search across millions of emails in milliseconds. Search by sender, date, attachment type, label, or any combination with advanced query syntax.

⏲
Rich Text Composer

Modern email composer with Markdown support, inline images, code blocks with syntax highlighting, templates, and scheduled send.

💾
IMAP/SMTP Bridge

JMAP proxy that connects to any existing IMAP/SMTP server. Use Koder Mail's modern interface with your current email provider.

📈
Calendar Integration

Built-in calendar with event invitations, RSVP handling, and free/busy scheduling. CalDAV support for syncing with external calendar apps.

💻
Contacts Management

Integrated address book with auto-complete, contact groups, CardDAV sync, and automatic contact creation from email interactions.

📦
Custom Domains

Use your own domain with automatic DNS configuration, SPF, DKIM, and DMARC setup. Send and receive from multiple domains and aliases.

🌐
Self-Hostable

Run your own email infrastructure with Koder Mail. Single binary deployment with built-in MTA, spam filtering, and virus scanning.

🛠
Mobile Progressive Web App

Responsive PWA that works offline, supports push notifications, and feels native on mobile devices. Install from the browser — no app store required.

JMAP: The Modern Email Protocol

Koder Mail uses JMAP, the successor to IMAP designed for the modern web. Push-based updates, efficient sync, and a clean JSON API make email integration a breeze.

  • Push notifications instead of polling — instant updates
  • Efficient delta sync transfers only changes
  • JSON over HTTP — no binary protocol complexity
  • Full spec compliance (RFC 8620, 8621)
# JMAP API — fetch mailboxes and messages
session = await fetch("https://mail.koder.dev/.well-known/jmap", {
  headers: { Authorization: `Bearer $#{token}` }
}).then(r => r.json())

response = await fetch(session.apiUrl, {
  method: "POST",
  body: JSON.stringify({
    using: ["urn:ietf:params:jmap:core",
            "urn:ietf:params:jmap:mail"],
    methodCalls: [
      ["Mailbox/get", { accountId }, "a"],
      ["Email/query", {
        accountId,
        filter: { inMailbox: inboxId },
        sort: [{ property: "receivedAt", isAscending: false }],
        limit: 50
      }, "b"]
    ]
  })
})

OIDC Single Sign-On

Integrate Koder Mail with your identity provider for secure, passwordless authentication. Users sign in once and access all Koder services.

  • Compatible with any OIDC provider (Keycloak, Auth0, Okta)
  • Automatic user provisioning from identity directory
  • MFA enforcement through your identity provider
  • Session management with configurable timeouts
# Koder Mail OIDC configuration
# /etc/koder-mail/config.toml

[auth]
method = "oidc"

[auth.oidc]
issuer        = "https://auth.company.com/realms/main"
client_id     = "koder-mail"
client_secret = "$#{OIDC_SECRET}"
scopes        = ["openid", "email", "profile"]
auto_create   = true

# Map OIDC claims to email accounts
[auth.oidc.mapping]
email    = "email"
name     = "name"
groups   = "groups"

IMAP Bridge: Use Any Backend

Don't want to switch email servers? Koder Mail's JMAP proxy connects to any existing IMAP/SMTP server, giving you a modern interface on top of your current infrastructure.

  • Connect to Gmail, Exchange, Dovecot, or any IMAP server
  • JMAP translation layer for modern client access
  • Local caching for offline access and fast search
  • Gradual migration path — no big bang cutover
# Connect Koder Mail to existing IMAP server
$ koder-mail bridge add \
  --name "Company Exchange" \
  --imap "imap.company.com:993" \
  --smtp "smtp.company.com:587" \
  --auth "oauth2" \
  --tls "required"

Bridge configured. JMAP endpoint available at:
https://mail.koder.dev/jmap/company-exchange

# Check sync status
$ koder-mail bridge status
Company Exchange  ✓ Connected
  Mailboxes: 12 synced
  Messages:  48,291 cached
  Last sync: 2s ago (push active)

How It Compares

See how Koder Mail stacks up against the competition.

FeatureKoder MailGmailProton MailFastmailThunderbird
JMAP Protocol Support✓——✓—
OIDC Authentication✓Partial———
End-to-End Encryption✓—✓—Partial
Self-Hostable✓———✓
IMAP/SMTP Bridge✓—✓—✓
AI Smart Inbox✓✓———
Built-in Calendar✓✓✓✓✓
Custom Domains✓Partial✓✓—
Progressive Web App✓✓✓✓—
Open Source✓—Partial—✓

Frequently Asked Questions

JMAP (JSON Meta Application Protocol) is the modern replacement for IMAP, standardized as RFC 8620/8621. It uses JSON over HTTP with push-based updates, making email sync faster, more efficient, and easier to implement than the 30-year-old IMAP protocol.

Yes. Koder Mail includes a JMAP proxy that connects to any IMAP/SMTP server — Gmail, Exchange, Dovecot, Postfix, or any other. You get the modern Koder Mail interface while keeping your existing email infrastructure.

Like Proton Mail, Koder Mail offers end-to-end encryption with zero-knowledge architecture. Additionally, Koder Mail supports standard PGP and S/MIME (not just proprietary encryption), interoperates with any PGP-capable client, and is fully self-hostable.

Yes. The self-hosted version includes a complete MTA for sending and receiving email, with built-in SPF, DKIM, DMARC validation, spam filtering (rspamd integration), and virus scanning. You can run a complete email stack from a single binary.

Yes. mail.koder.dev offers managed email with custom domains, 50GB storage, and all features included. Free tier includes 5GB and one custom domain. Pro plan at $4.99/month includes 50GB, unlimited domains, and priority support.

Yes. Koder Mail includes migration tools that import all your emails, folders, labels, contacts, and calendar events from Gmail, Outlook/Exchange, Yahoo Mail, and any IMAP server. Migration preserves dates, read status, and folder structure.

Ready to get started?

Secure Email, Modern Protocol