The information in this article applies to:
- Microsoft Exchange Server, versions 4.0, 5.0, and 5.5
SYMPTOMS
If a Microsoft Exchange Server is removed from a Microsoft Exchange Site and
Organization and then re-installed using a different Organization and Site
name, messages sent to that Server may appear to loop or stick in the Microsoft
Exchange Server Message Transfer Agent (MTA) for a long period of time.
Eventually, they are returned to their originators with a Non-Delivery Report
(NDR) that includes the following text:
The recipient could not be processed due to congestion in the message
transfer service.
RESOLUTION
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There are two scenarios that can cause this type of behavior:
- Once a Microsoft Exchange Server is removed from the Site and Organization
that it was replicating with, the other Servers in the Site will not
instantly know that the Server was removed. Users will be able to send
messages to recipients on the old Server and the messages will be routed
to the proper queue. They will wait there until their internal 512 hop
count is exceeded and then NDR with the above error message. To prevent
this, once a Server is removed from the Organization or Site, force a
replication session among all of the remaining Servers so that users from
the old Server will no longer appear in the Global Address List (GAL).
- Another scenario is when a Server is removed from a Site, the sitename is
changed, and then the Server is re-added to the Organization. Messages that
are pending to go to the old Site will see that the Site is back, based on
the MTA name. The MTA has no method of detecting that the messages are
invalid since the old MTA name still exists as a valid route. Again, the
messages will loop until their 512 hop limit is exceeded and they NDR. This
problem is also easily avoidable. Once the Server is removed from the Site,
delete any messages pending for users on the old Server. This can be done
by going to each Server in the Site and looking at its pending queue to the
old Server. When the messages are deleted from the queue, they will NDR
back to the originators. This behavior is by product design.
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