rspamd-iscan

The main repository is at fho/rspamd-iscan. This repo provides the Docker image and Helm chart.

rspamd-iscan is a daemon that monitors IMAP mailboxes and sends new mails to Rspamd for spam analysis and training. It decouples spam filtering from mail delivery — allowing the MDA, Rspamd, and rspamd-iscan to run on entirely separate hosts. For example, you can filter mails on the IMAP server of your third-party provider using your self-hosted Rspamd instance. It is similar to isbg but uses Rspamd instead of SpamAssassin.

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Quick start (Docker)

Build and run locally:

docker build -t rspamd-iscan .

docker run -d \
  --name rspamd-iscan \
  -v /path/to/config.toml:/etc/rspamd-iscan/config.toml \
  rspamd-iscan

Or pull the pre-built image:

docker pull guestros/rspamd-iscan

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Helm (Kubernetes)

The Helm chart deploys the full stack: Rspamd + rspamd-iscan, with an optional in-cluster Redis.

Install

Copy helm/examplevalues.yaml, fill in your IMAP details and password, then install:

cp helm/examplevalues.yaml myvalues.yaml
# edit myvalues.yaml

helm install rspamd-iscan oci://ghcr.io/justinguese/rspamd-iscan \
  -f myvalues.yaml -n spamfilter --create-namespace

No manual secret creation needed — all credentials go in your values file and are stored in a Kubernetes Secret by Helm. The Rspamd controller password is auto-generated on first install.

All options are documented in helm/rspamd-iscan/values.yaml.

IMAP mailbox setup

The rspamdIscan.mailboxes section controls which IMAP folders are used:

Key	Purpose	Default
scan	Incoming unprocessed mail — rspamd-iscan watches this	INBOX.Unscanned
inbox	Clean mail is moved here after scanning	INBOX
spam	Detected spam is moved here	INBOX.Junk
ham	Drop false positives here to train Rspamd	INBOX
undetected	Drop missed spam here to train Rspamd	INBOX.Undetected
backup	Archive copy of all processed messages	INBOX.BackupMailbox

Note: Undetected, Unscanned, and BackupMailbox are non-standard folders — most providers won't create them automatically. Create them manually in your mail client or provider's webmail before deploying.

Recommended mail provider setup: Configure a server-side rule to deliver all incoming mail into the scan folder instead of INBOX. rspamd-iscan will then sort it automatically.

I am using Hostinger Email (~€1/month) — good, cheap, and works great with this setup. If this saved you some time, feel free to use the referral link and buy me a coffee ☕

How training works

• Missed spam in inbox → drag it to undetected — rspamd-iscan will use it as a spam training example
• Legitimate mail in spam → drag it to ham — rspamd-iscan will use it as a ham training example

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CI / Docker image

The GitHub Actions workflow builds and publishes a new Docker image automatically:

• On every push to main (e.g. Dockerfile changes)
• Weekly, if the upstream repo (fho/rspamd-iscan) has new commits — checked via commit SHA caching, so no unnecessary rebuilds

To publish images from your own fork, configure:

1. Settings → Secrets and variables → Actions
2. Add variable DOCKERHUB_USERNAME — your Docker Hub username
3. Add secret DOCKERHUB_TOKEN — a Docker Hub access token