Exchange - Scoped Send Connector meaning and how to manually change Routing weight overriding Ad Sites costs

On Exchange Server about hub transport connector for outgoing email there is an option that some time it could be misunderstood, it is "Scoped Send Connector" checkbox.

When you mark a send connector as scoped, this means it can only be used by Exchange 2007/2010 hub transport or Exchange 2013 mailbox servers in the same Active Directory site as the send connector.  

If not selected, the connector can be used by all transport servers in the Exchange environment.

A Send Connector is not bound/limited to any specific Active Directory site but a merely object in Active Directory!

Example:

Let us suppose to have an AD Site called "Contoso HQ" and the site has 4 transport servers whether they be Exchange 2010 Hub Transport servers or Exchange 2013 mailbox servers.  

Two of these servers are marked as source servers of the scoped send connector and two aren't.  

The two servers which are a member as a source server of the send connector can obviously use the send connector.  The other two transport servers in the same Active Directory site which are not source servers can also use the scoped send connector, all other transport servers in other sites - bad luck!

Unchecking as scoped it means that transport servers in other sites can relay through the send connector if there is no closer option for external mail relay.

To get AD Site and View Cost:

Get-AdSiteLink

Almost all are aware of the fact that Exchange 2010 uses AD Sites and Services information to route emails from one AD site to another.

So you could think to change AD Sites costs but, in large organizations, as changing the existing AD site costs may affect the production network or the AD team just don’t want to make any changes.

Exchange 2010 (infact 2007 as well) has a solution for the above scenario. There is a way by which you can change the email routing without making any changes to the AD site link costs. It is known as “Exchange Cost” and is not configured by default.

This is the command syntax:

Set-ADSiteLink –identity “link name” –ExchangeCost “cost”

The maximum message size that passes through a site link can be restricted as well. It will come in handy if the link between the site is not great. Run the command below to specify a size limit for communications between various AD sites.

Set-ADSiteLink –identity “link name” –MaxMessageSize “size”

[original Article http://clintboessen.blogspot.fr/2014/01/what-are-scoped-send-connectors.html]

[http://theucguy.net/change-email-routing-using-exchange/]