Restricting Hub Transport Server selection using SubmissionServerOverrideList

I had a great question today:

I have three Hub Transport Servers,and one Mailbox Server, and I want   Hub Transport servers one and two used for load balanced mail delivery. Hub Transport Server three should never be used, except for mail relaying.


Obviously one of the design features of Exchange 2010 is the ability for transport load to auto-load balance, once more than one Hub Transport server is introduced. How do you take one or more of the Hub Transport Servers out of selection, without moving the affected Hub Transport server to it’s own AD site?

The Mailbox Server hosts the Mail-Submission Service, which notifies a Selected Hub Transport server than new mail is available for delivery. As such the mailbox server object holds an attribute called “SubmissionServerOverrideList”. SubmissionServerOverrideList allows you to specify which Hub Transport servers a mailbox server may use to route mail.

an Example of this may be:

Set-MailboxServer –Identity –SubmissionServerOverrideList,

This works equally well on Exchange 2007 and Exchange 2010. ONE TINY CAVEAT THOUGH: Set-MailboxServer does not check if you’re populating SubmissionServerOverrideList with a valid hub-transport server, only if you’re specifying a valid Exchange server.

Nicolas Blank

Nicolas is an Architect, author, and speaker focused on all things Exchange and Cloud at NBConsult. With over 16 years of experience on Exchange, Nicolas consults to customers globally on cloud based and on-premises Exchange as well as ISVs building Exchange focused products. Nicolas has extensive experience using Azure to create public and private Azure based offerings leveraging cloud based principles and common sense. Nicolas currently holds status of MCM Exchange 2010, Office 365 (Microsoft Certified Master), MCSM Exchange 2013, and has been awarded Microsoft MVP (Most Valuable Professional) for Microsoft Exchange since March 2007. Nicolas has co-authored "Microsoft Exchange Server 2013: Design, Deploy and Deliver an Enterprise Messaging Solution," published by Sybex. Nicolas blogs regularly on Exchange and messaging topics at, tweets at @nicolasblank, and is the founder of and a contributor to IT Pro Africa and @itproafrica

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