Extra Hops When Routing Mail Between E2K3 Servers   

Problem: A user on server A sends a message to a user on server B. When 
looking at the mail header information, the message always goes through 
server C before arriving on server B.

Desired Result: Messages sent from any E2K3 server go from the source server 
to the destination server without additional hops.

Configuration: (4) E2K3 Enterprise servers and (3) E5.5 Enterprise servers 
in a single administrative and routing group. All servers are on one network. 
There is an Internet Mail SMTP connector for each E2K3 server and a IMC 
connector for each E5.5 server. All E2K3 server SMTP connectors point to 
their own local virtual SMTP server as the local bridgehead server. Server C 
as mentioned in the example above is the routing group master and is the one 
all mail appears to flow through before being delivered to the proper server 
unless the source and destination mailbox are located on the same E2K3 
server. All user mailboxes reside on one of the E2K3 servers, public folders 
and off line address book generation etc. are still on the E5.5 servers and 
have not been migrated yet. An ADC connector is in place to keep everything 
updated between the servers. 

Your help is appreciated.
-- 
Rob
Systems Engineer

date: Mon, 25 Apr 2005 12:06:02 -0700   author:   wstfeng alias

RE: Extra Hops When Routing Mail Between E2K3 Servers   

Hi Rob,

Firstly, please use Message Tracking Center to track the message sent from 
A to B. Sometimes we may see server C's address has been stamped on the 
message header, but the message has not traveled to server C actually. So 
please use Message Tracking Center to verify this factor first.

XADM: Using the Message Tracking Center to Track a Message
http://support.microsoft.com/?id=262162

After reviewing your configuration, I suspect this problem is caused by the 
SMTP connectors. 

As you may know, the SMTP connector works for the whole routing group. If 
you have assigned multiple SMTP connectors and multiple bridgeheads in one 
routing group, then the master server, which holds the link list, 
determines the mail routing depending on the cost value. Thus, usually, in 
order to avoid message looping, one SMTP connector in a routing group is 
enough. All outbound messages will be sent to this bridgehead for being 
relay to internet. If all the servers can connect to internet directly, 
then we do not need SMTP connectors at all. The SMTP virtual server on each 
Exchange server can handle its own mail flow properly. Please have a look 
at:

319407 HOW TO: Use SMTP Connectors to Connect Routing Groups in Exchange 
2000
http://support.microsoft.com/?id=319407

So, the possible cause of your problem is: (A-B) message is send to the 
SMTP connector on C first because it is the same cost value as the SMTP 
connectors on A and B, and then relay to B via C's SMTP virtual server.

The resolution is to remove all SMTP connectors if all the SMTP virtual 
servers can connect internet directly.

For more information, please refer to:

Planning an Exchange Server 2003 Messaging System
http://www.microsoft.com/downloads/details.aspx?FamilyId=9FC3260F-787C-4567-
BB71-908B8F2B980D&displaylang=en

Hope the info helps.

Regards,

Pat Cai
Microsoft Online Partner Support

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date: Tue, 26 Apr 2005 07:39:38 GMT   author:   (Pat Cai[MSFT])