Pakete: dovecot-lmtpd dovecot-sieve (Debian 9)

<file txt /etc/dovecot/conf.d/20-lmtp.conf>

protocol lmtp {
  mail_plugins = $mail_plugins sieve
}
</file>

<file txt /etc/dovecot/conf.d/90-sieve.conf>
…
plugin {
…
  sieve = file:~/sieve
…
</file>

Testen:
  doveconf -f service=lmtp mail_plugins