weird delivery report in 2.99.49p8

[Ambrose Li <acli@mingpaoxpress.com>]

I got a very strange delivery report just now. (At least I haven't seen
such a thing.)  The system is 2.99.49p8. 

The strange thing is the "Ok"...

---------- Forwarded message ----------
Date: Thu, 4 Dec 1997 18:07:54 -0500
From: The Post Office <postmaster@mingpaoxpress.com>
To: robban@robtex.com
Cc: The Post Office <postoffice@mingpaoxpress.com>
Subject: Delivery reports about your email

This is a collection of reports about email delivery
process concerning a message you originated. Please
[...]

Here is the report:

<local acli@mingpaoxpress.com acli@mingpaoxpress.com 65534>: Ok