Acabei de adicionar chaves de domínio à minha configuração do sendmail e tudo parece estar funcionando. No entanto, ao revisar o maillog, recebo uma tonelada quando um email é enviado ou recebido:
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Oct 4 09:42:44 servername sendmail[22036]: q94GgiGB022036: milter=dkim-filter, action=header, continue
Alguma pista sobre o que pode estar causando isso? Não é um problema enorme, mas eu prefiro não ter muitas linhas toda vez que um e-mail for enviado.
dkim-filter tem uma opção -l. Se você omitir esse argumento, as chances são de que essas linhas de log desaparecerão.
Outra maneira possível é instalar syslog-ng e, usando as diretivas de filtragem, você pode remover linhas antes que elas sejam registradas. (Eu gosto do último como você pode remover outros programas de saída sem sentido também.)