Jorgen Lundman:
> Experimental patch aside, we have changed the L7 health-check [1] to be L4
> port-open checks instead. This stops Postfix from sitting in flush since no
> command has been issued.
This still leaves your system vulnerable to a trivial DOS: force
the sender to sit in timed-write for $smtpd_timeout seconds.
Workaround: in write_wait(), return -1 when write(fd, buf, 0) returns
-1, regardless of the errno.
And please report a bug to Oracle. This bug will affect other
software, too.
Wietse