To allow cyrus-imapd to send emails (a sieve reject rule for example) the
following module is needed.

module mycyrusimapd 1.0.8;

require {
  class dir { getattr search add_name read remove_name write };
  class file { read getattr create lock rename unlink write execute
execute_no_trans };
  class lnk_file read;
  type cyrus_t;
  type etc_mail_t;
  type mqueue_spool_t;
  type sendmail_exec_t;
  type sbin_t;
  role system_r;
};

allow cyrus_t sbin_t:dir search;
allow cyrus_t sbin_t:lnk_file read;
allow cyrus_t etc_mail_t:dir { getattr search };
allow cyrus_t etc_mail_t:file { getattr read };
allow cyrus_t mqueue_spool_t:dir { add_name getattr read remove_name search write };
allow cyrus_t mqueue_spool_t:file { create getattr lock read rename unlink write };
allow cyrus_t sendmail_exec_t:file { execute read execute_no_trans };