mbox_path = string_sprintf("%s/scan/%s/%s.eml",
spool_directory, message_id, message_id);
if (mbox_fname) *mbox_fname = mbox_path;
mbox_path = string_sprintf("%s/scan/%s/%s.eml",
spool_directory, message_id, message_id);
if (mbox_fname) *mbox_fname = mbox_path;