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Rspamd
What it is
Rspamd is an open-source email security engine for filtering phishing, business email compromise, malicious attachments, and spam. It scores messages using reputation, sender authentication, content analysis, and machine learning, with checks for SPF, DKIM, DMARC, and ARC. It can integrate with ClamAV and commercial antivirus engines, and works with Postfix, Exim, and Sendmail. Administrators can create custom filtering rules through its Lua API, maps, and selectors. The gateway deployment can run on-premises, keeping message data in the user's environment without mandatory vendor cloud use. ClickHouse and Elasticsearch integrations provide visibility into attack patterns and detection rates. The engine is open source under Apache 2.0. The free self-hosted core is available without a listed price. Scale is listed at £100 + VAT/month for 5K mailboxes. Pricing depends on protected mailbox count; paid plans include support from core engineers, with SLA options for enterprise users. Previous stable-branch support ends when a new major release becomes stable, and old releases are unsupported.
For and against
For
- Open-source engine under Apache 2.0
- On-premises deployment without mandatory vendor cloud
- Checks SPF, DKIM, DMARC, and ARC
- Custom rules supported through Lua API
Against
- Scale plan starts at £100 + VAT/month
- Pricing depends on protected mailbox count
- Old releases are not supported
The verdict
Rspamd combines email filtering, authentication checks, and malware-scanning integrations in a self-hosted engine. Organizations should account for mailbox-based pricing and the stated release-support limit.
Who it suits
Rspamd suits organizations operating their own mail systems that want gateway filtering and on-premises deployment. It may also suit administrators who need custom rules or integrations with mail servers and analytics tools.
Plans and prices
Open-source Rspamd
Open-source engine · self-hosted
Read 15 Oct 2026 · rspamd.com
Scale
5K mailboxes · scalable to your demands · premium fuzzy database and bulk service
Read 15 Oct 2026 · rspamd.com
Enterprise
50K+ mailboxes · Rspamd Console · neural/FastText models · priority support and SLA
Read 15 Oct 2026 · rspamd.com
Hosted
Custom mailboxes · fully managed deployment · runs on customer or Rspamd infrastructure
Read 15 Oct 2026 · rspamd.com
On the record
- AI integrations
- The documented feature set includes GPT integration, custom HTTP classifiers and verdict aggregation with existing rules.docs.rspamd.com · read 15 Oct 2026
- Analytics integrations
- Rspamd can export scan data to ClickHouse, Elasticsearch and custom webhooks.docs.rspamd.com · read 15 Oct 2026
- Antivirus integrations
- The antivirus module supports scanners including ClamAV, Kaspersky, Sophos, Avast, Avira, MetaDefender Cloud and VirusTotal.docs.rspamd.com · read 15 Oct 2026
- Authentication
- Its sender authentication checks include SPF, DKIM, DMARC, and ARC.rspamd.com · read 7 Oct 2026
- Bayesian classifier
- Bayes classification uses token statistics, Redis storage, per-user training and optional automatic learning.docs.rspamd.com · read 15 Oct 2026
- Company
- The site identifies the company as Rspamd Ltd.rspamd.com · read 7 Oct 2026
- Company headquarters
- Crunchbase lists RSPAMD LTD in Cambridge, Cambridgeshire, United Kingdom.crunchbase.com · read 15 Oct 2026
- Company legal name
- Crunchbase identifies the legal name as RSPAMD LTD, an active private for-profit company.crunchbase.com · read 15 Oct 2026
- Company size
- Crunchbase lists the company size as 1–10 employees.crunchbase.com · read 15 Oct 2026
- Custom rules
- Rspamd supports custom filtering rules through its Lua API and configurable maps and selectors.rspamd.com · read 7 Oct 2026
- Deployment
- The project describes the engine as runnable on-premises, with message data staying in the user's environment and no mandatory vendor cloud dependency.rspamd.com · read 7 Oct 2026
- Documentation depth
- Documentation includes installation, configuration, modules, workers, tutorials, developer architecture and protocol material, a Lua API reference and FAQ.docs.rspamd.com · read 15 Oct 2026
- Email authentication
- Rspamd validates SPF, DKIM, DMARC and ARC, including cryptographic signing capabilities.docs.rspamd.com · read 15 Oct 2026
- Filtering
- It combines reputation, sender authentication, content analysis, and machine learning to score and filter messages.rspamd.com · read 7 Oct 2026
- Filtering methods
- The system combines Bayesian statistics, neural networks, fuzzy hashing, DNS blocklists and rule-based content checks.docs.rspamd.com · read 15 Oct 2026
- Greylisting
- Greylisting temporarily rejects unknown sender-recipient pairs and keeps triplet state in Redis.docs.rspamd.com · read 15 Oct 2026
- License
- The project is licensed under Apache License 2.0, allowing commercial use, modification and redistribution with no warranty.docs.rspamd.com · read 15 Oct 2026
- Limit: add-on compatibility
- Thunderbird reviewers reported that the add-on stopped working with Thunderbird 115.3.1 and that its instructions were difficult for non-programmers.services.addons.thunderbird.net · read 15 Oct 2026
