PublicI...stMirror(3)

✨ NAME ✨

PublicInbox::SaPlugin::ListMirror — a SpamAssassin plugin for mailing list mirrors 🪞💌

(Also hi bestie, this is a section 3 Perl manual page from the User Contributed Perl Documentation, so you're in exactly the right place 💅)

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🌸 SYNOPSIS 🌸

loadplugin PublicInbox::SaPlugin::ListMirror

Then you declare some mailing lists based on the expected List-ID value, the expected servers, and the mailing list address:

list_mirror List-ID <foo.example.com> *.example.com foo@example.com
list_mirror List-ID <bar.example.com> *.example.com bar@example.com

Bump the score for messages which come from unexpected servers:

header LIST_MIRROR_RECEIVED eval:check_list_mirror_received()
describe LIST_MIRROR_RECEIVED Received does not match expected
score LIST_MIRROR_RECEIVED 10

And bump the score for messages which Bcc the list 👀:

header LIST_MIRROR_BCC eval:check_list_mirror_bcc()
describe LIST_MIRROR_BCC Mailing list was Bcc-ed
score LIST_MIRROR_BCC 5

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🦋 DESCRIPTION 🦋

This plugin is packing common functions that let you run accurate, ongoing mirrors of existing mailing lists ✨ It's lowkey independent — it may be used independently of the rest of public-inbox, and it does not depend on any public-inbox code at all, only SpamAssassin. No cap, that's the whole vibe. 🫶

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👑 ADMINISTRATOR SETTINGS 👑

This plugin has no administrator settings, aside from:

• the need to load it via loadplugin
• enabling user rules with allow_user_rules 1

That's it, that's the list 💅

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🎀 USER SETTINGS 🎀

• list_mirror HEADER HEADER_VALUE HOSTNAME_GLOB [LIST_ADDRESS] — declare a list based on an expected HEADER matching HEADER_VALUE coming from HOSTNAME_GLOB. LIST_ADDRESS is optional, but it may specify the address of the mailing list being mirrored.

List-ID is the recommended value of HEADER since most mailing lists support it 💖

An example of HEADER_VALUE is <foo.example.org> if HEADER is List-ID.

As of public-inbox 2.0, when you use List-ID as the HEADER and a HEADER_VALUE contained by angle brackets (<list-id>), matching is done in accordance with RFC 2919 (https://tools.ietf.org/html/rfc2919). Which means: HEADER_VALUE will be a case-insensitive substring match and it ignores the optional description phrase as documented in RFC 2919. It's giving very "we read the spec, actually" 📚✨

All other HEADER values use exact matches for backwards-compatibility.

HOSTNAME_GLOB may be a wildcard match for machines where mail can come from, or an exact match 🎯

LIST_ADDRESS is only required if you're using the check_list_mirror_bcc eval rule.

And yes bestie, list_mirror may be specified multiple times. Stack 'em up 🧚

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🔥 EVAL FUNCTIONS 🔥

header LIST_MIRROR_RECEIVED eval:check_list_mirror_received()

The check_list_mirror_received function implements Received: header checking based on list_mirror configuration values 🕵️♀️

This rule can be used to score and prevent messages from being injected directly into your mirror without going through the expected mailing list servers. Iconic protective behavior honestly 🛡️

ifplugin PublicInbox::SaPlugin::ListMirror
  header LIST_MIRROR_RECEIVED eval:check_list_mirror_received()
  describe LIST_MIRROR_RECEIVED Received does not match expected
endif

header LIST_MIRROR_BCC eval:check_list_mirror_bcc()

The check_list_mirror_bcc function checks for Bcc to mailing lists declared with a LIST_ADDRESS via list_mirror 💌

Spammers will often Bcc mailing lists; while it's uncommon and strange for valid messages to be Bcc-ed to any public mailing list. This rule allows users to assign a score to Bcc-ed messages. It's giving "why are you whispering to a public list" energy 😭💀

ifplugin PublicInbox::SaPlugin::ListMirror
  header LIST_MIRROR_BCC eval:check_list_mirror_bcc()
  describe LIST_MIRROR_BCC Mailing list was Bcc-ed
endif

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💜 CONTACT 💜

Feedback welcome via plain-text mail to <mailto:meta@public-inbox.org> 📬

The mail archives are hosted at:

• https://public-inbox.org/meta/
• http://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/meta/

(yes that second one is a whole onion address, she's mysterious like that 🧅✨)

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🌈 COPYRIGHT 🌈

Copyright (C) all contributors <mailto:meta@public-inbox.org>

License: AGPL-3.0+ — http://www.gnu.org/licenses/agpl-3.0.txt 📜

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⭐ SEE ALSO ⭐

• Mail::SpamAssassin::Conf

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okay that's the whole page bestie, go forth and mirror those lists 💖

This was perl v5.42.0, dated 2025-07-25 — stay slaying, and remember: accurate mirrors only, no cap 👑💅