DOCUMENT:Q168781  04-SEP-1999  [exchange]
TITLE   :XFOR: Sending to SMTP Gets Immediate NDR 550 Error Message
PRODUCT :Microsoft Exchange
PROD/VER:winnt:4.0,5.0
OPER/SYS:
KEYWORDS:kbusage

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The information in this article applies to:

 - Microsoft Exchange Server, versions 4.0, 5.0 
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SYMPTOMS
========

All users are receiving Simple Mail Transfer Protocol (SMTP) mail; however,
sending to SMTP addresses results in an immediate non-delivery report (NDR) that
includes the following error message:

   550 Relaying mail to <recipient address> is not allowed.

WORKAROUND
==========

To work around this problem, do the following:

1. Confirm that the information store, the message transfer agent (MTA), and the
   Internet Mail Service (Internet Mail Connector in version 4.0) services are
   started, by going to Control Panel and double-clicking Services.

2. Check the configuration of the Internet Mail Service, especially the address
   space page, which should be a (*) or (a space).

3. Set all the categories of the Internet Mail Service diagnostic logging to
   maximum, and then send a message and check the event viewer for errors
   related to the Internet Mail Service.

4. Check the four queues of the Internet Mail Service, and the Exchange Server \
   Message Transfer Agent \ Internet Mail Service (Server Name) queue. If there
   are no messages in any of the queues, then the problem may be with the
   Internet Service Provider (ISP). Go to step 5.

   If there is no MTA object under the sender's server, the Exchange Server
   computer is a Standard Edition, and you must use the Performance Monitor \
   Qlength counter of the MSExchangeIMC Object in order to check the Internet
   Mail Service queues.

5. Send a message to the sender's ISP. If the sender does not receive the
   immediate NDR, then ask the sender to call his or her ISP and ask whether he
   or she received a message. If the ISP received the message, then the Internet
   Mail Service is able to send, and most probably the ISP is not routing or
   resolving names.


6. Run the NSLookup utility to confirm the domain name, MX records, and the
   A-Records of the sender's ISP.

7. Run the Telnet command to port 25 of the ISP according the Knowledge Base
   article: Q153119, "XFOR: Telnet to Port 25 of IMC to Test IMC Communication."

8. If the sender is using DNS, modify the Internet Mail Service to forward all
   messages to the host. If this works, then the Domain Name resolution is the
   cause of the problem.

9. If all the above fails, then delete and recreate the Internet Mail Service.

NOTE: After every step, stop and restart the Internet Mail Service and see
whether all messages are being delivered.

Additional query words:

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Keywords          : kbusage 
Technology        : kbExchangeSearch kbExchange500 kbExchange400 kbZNotKeyword2
Version           : winnt:4.0,5.0
Issue type        : kbprb

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