The Email Stack

Four battle-tested components working together

Postfix

High-performance Mail Transfer Agent (MTA). Handles SMTP submission (port 587), SMTPS (port 465), and outbound delivery with virtual mailbox support via MySQL.

Dovecot

IMAP and POP3 server for mailbox access. IMAPS (port 993) and POP3S (port 995) with TLS. MySQL-backed authentication and Maildir storage format.

OpenDKIM

Automatic DKIM email signing for every domain. Central milter service managed by the Kubernetes operator. Per-domain key rotation and DNS record generation.

Rspamd

Advanced spam filtering with Bayesian learning, Redis-backed caching, and milter integration. Automatically scans inbound and outbound mail for threats.

How DKIM Works in KubePanel

Automatic key generation, central management, operator-driven updates

1. Domain Created

Django generates an RSA DKIM keypair and stores it in a Kubernetes Secret (dkim-{domain}) in the kubepanel namespace.

2. Operator Reads

The Kopf operator detects the Domain CR with spec.email.dkimSecretRef and reads the private key from the referenced secret.

3. Central Update

Operator adds the key to the central dkim-keys Secret and updates KeyTable/SigningTable ConfigMaps with retry logic.

4. OpenDKIM Restart

Operator restarts the OpenDKIM deployment to pick up new keys. All outbound email for the domain is now DKIM-signed automatically.

Email Management Features

Everything you need to manage email for your hosted domains

Mailbox Management

Create and manage email accounts per domain. Support for primary domains and email-enabled aliases. Password hashing with SHA512-CRYPT.

  • Per-domain mail users
  • Package-based quotas
  • Active/inactive toggle
  • Import/export (MBOX format)

Email Forwarding

Create forwarding rules to redirect email from one address to another. Support for catch-all forwards and multiple destinations.

  • Source to destination rules
  • Active/inactive per rule
  • Alias-level quotas via packages

SMTP Firewall

Block spam at the SMTP level before it reaches mailboxes. Block senders by email, domain, or IP. Rate limiting per user to prevent abuse.

  • Sender/domain/IP blocking
  • Per-user rate limits
  • Real-time SMTP traffic view
  • Quick-block from traffic monitor

Email That Just Works

DKIM, SPF, DMARC configured automatically. Spam filtered by Rspamd. No manual setup required.