IP blacklisting admins can trust.

This blacklist is fundamentally different, because you will be able to create, maintain and control it yourself. It's all in your hands.

We have been running this system for over 14 years (since 2012) as freelance admins and decided to make it a public product because it provides such valuable services for us.

Read our whitepaper to understand the ideas behind MailMum: MailMum Whitepaper, or jump straight to the setup documentation to point your mail server at MailMum.

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How it works

Your mail server (Postfix, Exim, ...) performs a standard RBL-style DNS lookup against MailMum for every connecting client IP — the same way it would query a public list like Spamhaus. MailMum answers from your own blacklist/whitelist rules, and independently logs every single query as an auditable event.

  • Self-hosted & privately managed. The lists, the logging, and the audit trail belong entirely to you, not to a shared global reputation database.
  • No new infrastructure to run. Point the RBL check already built into your mail server at MailMum's DNS answer — see the setup documentation for Postfix, Exim, and others.
  • Built for scale. The ingestion pipeline is built to absorb bursts of DNS traffic (up to 1000 requests/second) without ever blocking the DNS response path itself.

Fine grained Blacklisting

  • We don't like global blacklists which harm admins.
  • Define the blacklist by your own down to server IP level.
  • Block whole networks like 192.168.0.0/24 to stop spammy providers.
  • See incoming mail traffic and decide based on data.
  • Organize it your way. It's all in your control!

Whitelist valuable resources

  • Whitelist IPs which are valuable to you.
  • Whitelist services which are important to your users and customers like Gmail, Mailchimp, etc.
  • Whitelisted IP-Ranges like 192.168.178.0/24.
  • Whitelisted IPs will never be blacklisted!

A complete audit trail

  • Every single DNS query hitting MailMum becomes a permanent, auditable record.
  • Source IP, destination server, pass/block status and timestamp for every connection attempt.
  • Automatic network/ownership information for incoming IPs, looked up and cached, so you don't have to look it up by hand.
  • Run your own RBL, and see everything it sees.

Multi-tenant by design

  • One MailMum installation can host many independent accounts.
  • Each account gets its own users, servers, lists and role-gated admins/viewers.
  • A natural fit for ISPs, hosting providers and MSPs running mail for many customers from one deployment.
  • See ISPs & hosting providers and MSPs for details.

E-Mail Analytics

  • See your incoming mail traffic.
  • Get analytics for better control.
  • See blocked mail traffic.
  • Build up history and reputation for your mail traffic.
  • Be notified if your IPs gets blacklisted or has unexpectedly heavy traffic.
  • Make your decisions based on data.

Who MailMum is for

What MailMum is not

  • Not a public/global reputation list. Every list is private to the account that created it — MailMum is the engine for running your own RBL, not a subscription to someone else's.
  • Not a Mail Transfer Agent (MTA). MailMum never sends, receives, relays or stores actual email. It only answers a DNS question that your existing MTA asks.
  • Not a content/spam filter. No message-body scanning, no Bayesian filtering — nothing SpamAssassin- or Rspamd-like. MailMum works purely at the IP/connection layer.
  • Not a firewall or network appliance. It doesn't sit inline and drop packets. It provides an answer; enforcement happens in your mail server's own configuration.

Stay in touch and get updates: