lmtp_rcpt_check_quota = yes silently blocks mail if quota check fails

I have a user which has a quota-check that fails with 'Internal error', if I enable lmtp_rcpt_check_quota, the mail is silently tempfailed.

Actually it looks like lmtp_rcpt_check_quota=yes suppresses normal Info/Error logging, even on Director. The MTA just gets " 451 4.3.0 xxxx@xxx.xxx Temporary internal error (in reply to end of DATA command)" from the director, but nothing is logged with lmtp_rcpt_check_quota=yes, anywhere.

-- Tom