DOCUMENT:Q133400  11-MAR-1999  [exchange]
TITLE   :XCON: Callout Schedule Not Affected by Message Priority
PRODUCT :Microsoft Exchange
PROD/VER:4.0 5.0
OPER/SYS:
KEYWORDS:kbenv

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Exchange Server, version 4.0 
-------------------------------------------------------------------------------

SUMMARY
=======

When you use the Microsoft Exchange Server message transfer agent (MTA), all
high-priority messages are moved to the top of the MTA work queue. However, the
MTA will transfer the messages depending on the schedule of the X.400 connector
or site connector used. In other words, all messages (high or low priority) wait
for the X.400 connector or site connector to establish the connection based on
the connector's schedule, but all high- priority messages will be at the top of
the work queue.

MORE INFORMATION
================

Each X.400 connector or site connector in Exchange Server has its own schedule,
which defines the specific times and blocks of time when the Exchange Server MTA
can initiate connections to the other Exchange Server MTA or foreign mail
system. This schedule can be set from the X.400 Connector's or Site Connector's
Schedule property page from the Microsoft Exchange Administrator program.

Whenever a message is handed over to the Exchange Server MTA, the MTA decides,
based on the routing information, which X.400 connector or site connector to use
to send the message. Once a connector is identified by the Exchange Server MTA,
the MTA moves the message into that connector's queue. If the message is high
priority, it is placed at the top of the queue for that connector.

The Exchange Server MTA cannot initiate a connection on the connector until the
connector's schedule permits it to do so. This means that all messages (with
either high or low priority) will sit in the queue until the X.400 connector or
site connector is scheduled to connect and transfer messages.

Example
-------

A site called DALLAS has the following connectors to three other sites:

 - X.400 connector to New York on X.25 transport stack is scheduled to connect
   only between 11:00 P.M. and 5:00 A.M.

 - Site connector to Seattle is scheduled to connect always.

 - X.400 connector to Houston on Remote Access Services (RAS) transport stack is
   scheduled to connect only between 8:00 P.M. to 8:00 A.M.

If a user at site Dallas sends a high-priority message to users in New York,
Seattle, and Houston at 10:00 A.M., the message is transferred at the following
times:

 - The message is put at the top of the work queue for the X.400 connector to
   New York because it is a high-priority message. The X.400 connector to New
   York will connect at 11:00 P.M. and will then move the message to New York.

 - Because the site connector to Seattle is scheduled to connect always, the
   message is moved as soon as the Exchange Server MTA hands the message to this
   connector.

 - The message is put at the top of the work queue for the X.400 connector to
   Houston because it is a high-priority message. The X.400 connector to Houston
   will initiate a call at 8:00 P.M. and then move the message to Houston.

Additional query words: TCP/IP TP4 DIAL faq


======================================================================
Keywords          : kbenv 
Technology        : kbExchangeSearch kbExchange400 kbZNotKeyword2
Version           : 4.0 5.0

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1999.