The Wiert Corner – irregular stream of stuff

Still learning postfix configuration, below are some links on how to enable various blacklists that use the RBL DNS (aka [WayBack] DNSBL) way of operations.

They are centered around using the of the [WayBack] Postfix Documentation entry reject_rbl_client listings:

• [WayBack] 5 main.cf – Postfix Configuration Parameters: reject_rbl_client
• [WayBack] Postfix SMTP relay and access control: Getting selective with SMTP access restriction lists
• [WayBack] Postfix manual – smtpd(8)
• [WayBack] 5 main.cf – Postfix Configuration Parameters: reject_rbl_client
• [WayBack] Postfix Stress-Dependent Configuration: Disconnect suspicious SMTP clients
• [WayBack] Postfix Per-Client/User/etc. Access Control
• [Archive.is] HISTORY

Basically reject_rbl_client is part of smtpd_client_restrictions.

TODO:

I need to dig further into some other blacklist options than reject_rbl_client: reject_rhsbl_client, reject_rhsbl_reverse_client, reject_rhsbl_sender or reject_rhsbl_recipient restriction.

Then I need to go through these links:

• [WayBack] Jim Seymour’s suggestions/examples for Postfix anti-UCE configuration. (Aka: Postfix Anti-UCE Cheat Sheet)
  • via [WayBack] SpamCop.net – SpamCop FAQ: Postfix
• [WayBack] Blocking SPAM (UCE) using Postfix
• [WayBack] Enable DNSBL service in Postfix to reduce spam
• [WayBack] spam – Blacklisted client: why did Postfix not reject this email? – Server Fault
• [WayBack] spam – Postfix reject_rbl_client Blacklists Not Working – Server Fault
• [WayBack] How To Block Spam Before It Enters A Postfix Server
• [WayBack] Postfix configure anti spam with blacklist – nixCraft
• [WayBack] HOWTO Stop spam using Postfix – LinuxReviews
• [WayBack] email server – How to enable RBL checking in postfix? – Server Fault
• [WayBack] More robust Postfix anti-spam configuration | Le Blog
• [WayBack] dnswl.org – E-Mail Reputation – Protect against false positives
  • [WayBack] dnswl.org Self Service

    Dnswl.org maintains a database of IP addresses (netranges) which are grouped into “DNSWL Records” (identified by a DNSWL Id, which is just an arbitrary number). This data is maintained through a combination of manual and automated actions – and by yourself.

    Using the Self Service portal you can “claim” DNSWL Ids as being yours After verification you can then request changes to IPs already stored, or add new IPs. For most parts, there will still be an editor approval before changes take effect.

    The Self Service portal is also used to manage the subscriptions which are required for certain types of users (eg for > 100’000 queries per day).

Some blacklist checking links:

• [WayBack] DNSBL Information – Spam Database and Blacklist Check
• [WayBack] IP Address Blacklist Check
• [WayBack] The Spamhaus Project – ZENzen.spamhaus.org should be the only spamhaus.org DNSBL in your IP blocklist configuration. You should not use ZEN together with other Spamhaus IP blocklists, or with blocklists already included in our zones (such as the CBL) or you will simply be wasting DNS queries and slowing your mail queue.

  Caution: Because ZEN includes the XBL and PBL lists, do not use ZEN on smarthosts or SMTP AUTH outbound servers for your own customers (or you risk blocking your own customers). Do not use ZEN in filters that do any ‘deep parsing’ of Received headers, or for anything other than checking IP addresses that hand off to your mailservers.

  • [WayBack] DNSBL Usage Terms – The Spamhaus Project
  • [WayBack] Blocklist Removal Center – The Spamhaus Project

–jeroen