[mlmmj] README.exim4 broken, needs update

[mlmmj] README.exim4 broken, needs update

[wulf]

Ahoi,

> The mlmmj.org website hosts a tutorial for exim 4 setup at
> http://mlmmj.org/docs/readme-exim4/

thanks to Florian for the dsearch syntax

I added multi-domain handling and debug Output

  you still need uniq user_parts
    info@list1.org
    info@list2.org
  will not work


Git comment
  Date:   Fri Mar 6 09:40:23 2026 +0100

  Update exim4 configuration hints
    - add debug output to router and transport
    - lookup changes according
        exim4 >= 4.94 taind behaver
      (Errors like "Tainted filename for search")
    - add router condition for setups with more than one domain (you need uniq
      local_parts over all your lists, but we do not want to match the transport on
      local_part@wrong.domain)

  hint
    - VERP config is not changed/updated, may not work


changed exim4 Readme
  https://codeberg.org/mlmmj/mlmmj/src/commit/690feb17265dc589f9b5275834dd76e251b47625/README.exim4.md

pull-request
  https://codeberg.org/mlmmj/mlmmj/pulls/88


Thanks for mlmmj
Grenouille

[mlmmj] README.exim4 broken, needs update

[Florian Berger]

The mlmmj.org website hosts a tutorial for exim 4 setup at http://mlmmj.org/docs/readme-exim4/ , 
which in turn refers to https://plonk.de/sw/mlmmj/README.exim4 as the most recent original (hence 
author Jakob Hirsch in cc:).

For the transport configuration, it advertises:

mlmmj_transport:
   [irrelevant lines left out]
   command = /usr/local/bin/mlmmj-recieve -F -L MLMMJ_HOME/${lc:$local_part}

This will no longer work in recent versions of exim (4.94 and above). exim now considers 
sender-derived data tainted, and will refuse to use them as-is. See

- https://git.exim.org/exim.git/blob/HEAD:/src/README.UPDATING
- https://www.exim.org/exim-html-current/doc/html/spec_html/ch-string_expansions.html

As far as the mlmmj config is concerned, $local_part is considered tainted.

It can reasonably be de-tainted by changing it into a directory lookup:

mlmmj_transport:
   [unchanged lines left out]
   command = /usr/bin/mlmmj-receive -F -L "${lookup {$local_part} dsearch,ret=full {MLMMJ_HOME}}"

To avoind exim users running into issues, the tutorial at plonk.de and mlmmj.org should be updated 
accordingly.


Thanks for considering,

Florian