TODO items for public-inbox

(Not in any particular order, and
performance, ease-of-setup, installation, maintainability, etc
all need to be considered for everything we introduce)

* general performance improvements, but without relying on
  XS or compiled code any more than we currently do.

* mailmap support (same as git) for remapping expired email addresses

* POP3 server, since some webmail providers support external POP3:
  https://public-inbox.org/meta/20160411034104.GA7817@dcvr.yhbt.net/

* TLS support for various daemons (including STARTTLS for NNTP and POP3)

* Combined "super server" for NNTP/HTTP/POP3 to reduce memory overhead

* Optional reply-to-list support for mirroring lists that want it :<
  Reply-to-list encourages the existing list as a single-point-of-failure,
  but having an extra mirror using public-inbox code is nice regardless.

* Configurable linkification for per-inbox shorthands:
  "$gmane/123456" could be configured to expand to the
  appropriate link pointing to the gmane.org list archives,
  likewise "[Bug #123456]" could be configured to expand to
  point to some project's bug tracker at http://example.com/bug/123456

* Support optional "HTTPS Everywhere" for mapping old HTTP to HTTPS
  links if (and only if) the user wants to use HTTPS.  We may also
  be able to configure redirects for expired URLs.

  Note: message bodies rendered as HTML themselves must NOT change,
  the links should point to an anchor tag within the same page,
  instead; giving the user options.

* configurable constants (index limits, search results)

* handle messages with multiple Message-IDs

* handle broken double-bracketed References properly (maybe)
  and totally broken Message-IDs

  cf.  https://public-inbox.org/git/20160814012706.GA18784@starla/

* portability to FreeBSD (and other Free Software *BSDs)
  ugh... https://rt.cpan.org/Ticket/Display.html?id=116615
  (IO::KQueue is broken with Danga::Socket)

* improve documentation

* linkify thread skeletons better
  https://public-inbox.org/git/6E3699DEA672430CAEA6DEFEDE6918F4@PhilipOakley/

* generate sample CSS for use with Stylish/dillo/etc

* streaming Email::MIME replacement: currently we generate many
  allocations/strings for headers we never look at and slurp
  entire message bodies into memory.
  (this is pie-in-the-sky territory...)

* use REQUEST_URI properly for CGI / mod_perl2 compatibility
  with Message-IDs which include '%' (done?)

* more and better test cases (use git fast-import to speed up creation)

* large mbox/Maildir/MH/NNTP spool import (see PublicInbox::Import)