This is useful in combination with `rspamd`

Copied from [here](/https://poolp.org/posts/2019-09-14/setting-up-a-mail-server-with-opensmtpd-dovecot-and-rspamd/)

## Installation

    $ doas pkg_add dovecot-pigeonhole


## Setup

On `/etc/dovecot/20-imap.conf`:

    protocol imap {
       mail_plugins = $mail_plugins imap_sieve
    }


On `/etc/dovecot/90-plugin.conf`:

    plugin {
      sieve_plugins = sieve_imapsieve sieve_extprograms
      sieve_global_extensions = +vnd.dovecot.pipe +vnd.dovecot.environment
      imapsieve_mailbox1_name = Junk
      imapsieve_mailbox1_causes = COPY APPEND
      imapsieve_mailbox1_before = file:/usr/local/lib/dovecot/sieve/report-spam.sieve
      imapsieve_mailbox2_name = *
      imapsieve_mailbox2_from = Junk
      imapsieve_mailbox2_causes = COPY
      imapsieve_mailbox2_before = file:/usr/local/lib/dovecot/sieve/report-ham.sieve
      imapsieve_mailbox3_name = Inbox
      imapsieve_mailbox3_causes = APPEND
      imapsieve_mailbox3_before = file:/usr/local/lib/dovecot/sieve/report-ham.sieve
      sieve_pipe_bin_dir = /usr/local/lib/dovecot/sieve
    }


On `/usr/local/lib/dovecot/sieve/report-ham.sieve`:

    require ["vnd.dovecot.pipe", "copy", "imapsieve", "environment", "variables"];
    if environment :matches "imap.mailbox" "*" {
      set "mailbox" "${1}";
    }
    if string "${mailbox}" "Trash" {
      stop;
    }
    if environment :matches "imap.user" "*" {
      set "username" "${1}";
    }
    pipe :copy "sa-learn-ham.sh" [ "${username}" ];


On `/usr/local/lib/dovecot/sieve/report-spam.sieve`:

    require ["vnd.dovecot.pipe", "copy", "imapsieve", "environment", "variables"];
    if environment :matches "imap.user" "*" {
      set "username" "${1}";
    }
    pipe :copy "sa-learn-spam.sh" [ "${username}" ];


On `/usr/local/lib/dovecot/sieve/sa-learn-ham.sh`:

    #!/bin/sh
    exec /usr/local/bin/rspamc -d "${1}" learn_ham


On `/usr/local/lib/dovecot/sieve/sa-learn-spam.sh`

    #!/bin/sh
    exec /usr/local/bin/rspamc -d "${1}" learn_ham


Grant mode 755 for the above shell scripts

Grant +w mode for the sieve directory (with -R)

Change directory to the sieve directory and run as root:

    $ doas sievec report-ham.sieve
    $ doas sievec report-spam.sieve


Restart dovecot with `rcctl restart dovecot`.