public-inbox design notes
-------------------------
Challenges to running normal mailing lists
------------------------------------------
1) spam
2) bounce processing of invalid/bad email addresses
3) processing subscribe/unsubscribe requests
Issues 2) and 3) are side-stepped entirely by moving reader
subscriptions to git repository synchronization and Atom feeds. There's
no chance of faked subscription requests and no need to deal with
confused users who cannot unsubscribe.
Use existing infrastructure
---------------------------
* public-inbox can coexist with existing mailing lists, any subscriber
to the existing mailing list can begin delivering messages to
public-inbox-mda(1)
* public-inbox uses SMTP for posting. Posting a message to a public-inbox
instance is no different than sending a message to any _open_ mailing
list.
* Existing spam filtering on an SMTP server is also effective on
public-inbox.
* Readers may continue using use their choice of NNTP and mail clients.
* Atom is a reasonable feed format for casual readers and is supported
by a variety of feed readers.
Why email?
----------
* Freedom from proprietary services, tools and APIs. Communicating with
developers and users of Free Software should not rely on proprietary
tools or services.
* Existing infrastructure, tools, and user familiarity.
There is already a large variety of tools, clients, and email providers
available. There are also many resources for users to run their own
SMTP server on a domain they control.
* All public discussion mediums are affected by spam and advertising.
There exist several good Free Software anti-spam tools for email.
* Privacy is not an issue for public discussion. Public mailing list
archives are common and accepted by Free Software communities.
There is no need to ask the NSA for backups of your mail archives :)
* git, one of the most widely-used version control systems, includes many
tools for for email, including: git-format-patch(1), git-send-email(1),
git-am(1), git-imap-send(1). Furthermore, the development of git itself
is based on the git mailing list: https://public-inbox.org/git/
(or
http://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/git/
for Tor users)
* Email is already the de-facto form of communication in many Free Software
communities..
* Fallback/transition to private email and other lists, in case the
public-inbox host becomes unavailable, users may still directly email
each other (or Cc: lists for related/dependent projects).
Why git?
--------
* git is distributed and robust while being both fast and
space-efficient with text data. NNTP was considered, but does not
support delta-compression and places no guarantees on data/transport
integrity. However, a read-only NNTP gateway is implemented.
* As of 2016, git is widely used and known to nearly all Free Software
developers. For non-developers it is packaged for all major GNU/Linux
and *BSD distributions. NNTP is not as widely-used nowadays.
Why perl 5?
-----------
* Perl 5 is widely available on modern *nix systems with good a history
of backwards and forward compatibility.
* git and SpamAssassin both use it, so it should be one less thing for
admins to install and waste disk space with.
* Distributing compiled binaries has higher costs for storage/cache
space is required for each architecture. Having a runnable,
source-only distribution means any user already has access to all
of our source.
Laziness
--------
* Stick to dependencies available in Debian main, this should make it
easier for potential users to install, and easier for distro
maintainers to pick up.
* A list server being turned into an SMTP spam relay and being
blacklisted while an admin is asleep is scary.
Sidestep that entirely by having clients pull.
* Eric has a great Maildir+inotify-based Bayes training setup
going back many years. Document, integrate and publicize it for
public-inbox usage, encouraging other admins to use it (it works
as long as admins read their public-inbox).
* Custom, difficult-for-Bayes requires custom anti-spam rules.
We may steal rules from the Debian listmasters:
svn://anonscm.debian.org/pkg-listmaster
* Full archives are easily distributable with git, so somebody else
can take over the list if we give up. Anybody may also run an SMTP
notifier/delivery service based on the archives.
* Avoids bikeshedding about web UI decisions, GUI-lovers can write their
own GUI-friendly interfaces (HTML or native) based on public archives.
Web notes
---------
* Getting users to install/run any new tool is difficult.
The web views must be easily read/cache/mirror-able.
* There may also be a significant number of webmail users without
an MUA or feed reader; so a web view is necessary.
* Expose Message-ID in web views to encourage replies from drive-by
contributors.
* Raw text endpoint allows users to write client-side endpoints
without hosting the data themselves (or on a different server).
What sucks about public-inbox
-----------------------------
* Lack of push notification. On the other hand, feeds seem popular.
* some (mostly GUI) mail clients cannot set In-Reply-To headers
properly without the original message.
Scalability notes
-----------------
See the public-inbox-v2-format(5) manpage for all the scalability
problems solved.
Copyright
---------
Copyright 2013-2021 all contributors
License: AGPL-3.0+