@jmtd I use Dovecot's sieve for sorting.

@jmtd i think exim filters can do what you want though it might require changes to your exim.conf

for your killfile, i think you need to use fancy string expansions eg foranyaddress ${readfile{/path/to/killfile}{,}}

@jmtd for pipes, the behaviour is configured on the pipe transport that is named in the redirect router that handles the .forward file

in the default config file there’s a userforward: router with pipe_transport = address_pipe

https://www.exim.org/exim-html-current/doc/html/spec_html/ch-the_default_configuration_file.html

the pipe transport has lots of options controlling what to do when the command behaves in certain ways https://www.exim.org/exim-html-current/doc/html/spec_html/ch-the_pipe_transport.html

@jmtd for calendar years you can use something like ${substr{0}{4}{$tod_log}}

@jmtd hmm yeah the filtering and header rewriting is not really doable in a filter, needs hacks in exim.conf