XFOR: An Unexpected Response (500) Was Received from News Server Ninou.dns.micros (166642)

SYMPTOMS

When you perform an inbound or outbound push from the Network News Transfer Protocol (NNTP) server to another server, some articles may cause the store to stop responding during the inbound newsfeed. The following error message may be logged in the application event log:

   An unexpected response (500) was received from news server
   ninou.dns.microsoft.com.

STATUS

Microsoft has confirmed that this is a problem in Microsoft Exchange Serverversion 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

MORE INFORMATION

The ending sequence parsing code in NNTP is confused if the following occurs:

A post (or Ihave newsfeed) comes into a newsgroup that the poster does not have access to.
The post is greater than 1K in size.
The character at offset 1k in the posted article is 0xA.
The last 3 characters (before the real ending sequence) of the article are ". 0xD 0xA" ("." 0x0d 0x0a).
The article is rejected.

Exchange Server prematurely terminates the post and therefore corrupts the data stream between the client and server. This can also happen with messages larger than the maximum message size. NNTP is treating the last 5 bytes of an article as commands, and as a result sends the following error message to the client:

500 command not recognized