Networking

Changes in Exchange 2007 transport architecture

In Mail delivery changes in Exchange 2007, I outlined how Exchange 2007 has been re-engineered in a big way due to 2007's role-based nature, which necessitated a reworking of how different Exchange services communicate. This chart details the protocol used to communicate between various roles.

In Mail delivery changes in Exchange 2007, I outlined how Exchange 2007 has been re-engineered in a big way due to 2007's role-based nature, which necessitated a reworking of how different Exchange services communicate.

The chart below outlines the protocol used to communicate between various roles.

Roles and communications matrix

From/To Mailbox Hub Transport(Same Site) Hub Transport(Diff.Site) Client Access Unified Messaging Edge
Mailbox N/A MAPI/RPC N/A MAPI/RPC MAPI/RPC N/A
Hub Transport(Same Site) MAPI/RPC SMTP/TLS SMTP/SSL MAPI/RPC N/A SMTP/TLS
Hub Transport(Diff. Site) N/A SMTP/SSL SMTP/TLS N/A N/A N/A
Client Access MAPI/RPC MAPI/RPC N/A N/A N/A N/A
Unified Messaging MAPI/RPC N/A N/A N/A N/A N/A
Edge N/A SMTP/TLS N/A N/A N/A N/A

Note that there are three primary communication mechanisms:

  • MAPI/RPC
  • SMTP/TLS
  • SMTP/SSL

Where you see N/A, this means that the roles do not talk directly to one another. For example, the Unified Messaging server role talks solely to the Mailbox Server role and never to the Hub Transport server role.

Transition warning: Don't delete administrative groups

Many organizations are transitioning to Exchange 2007. Bear in mind that Microsoft specifically uses the word transition to describe a process by which an organization moves from Exchange 2000 or Exchange 2003 to Exchange 2007.

Toward the tail end of this transition process, vestiges of the legacy Exchange organization—Exchange 2000/2003 servers, routing groups, etc.—are purged from Active Directory and from the infrastructure. However, exercise some caution before you expunge everything.

In particular, if you’re running legacy Outlook clients (Outlook 2003 and below) don’t remove the administrative groups that once held mailboxes in your legacy Exchange organization. Users’ Active Directory LegacyExchangeDN field continues to point to the legacy administrative group and versions of Outlook before Outlook 2007 use this field in order to find free/busy information.

If you delete these administrative groups, legacy Outlook users may not be able to find or publish free/busy information. Users who have been migrated to Outlook 2007 are not affected by this problem since Outlook 2007 uses Exchange 2007’s new capabilities to provide real-time free/busy information.

About

Since 1994, Scott Lowe has been providing technology solutions to a variety of organizations. After spending 10 years in multiple CIO roles, Scott is now an independent consultant, blogger, author, owner of The 1610 Group, and a Senior IT Executive w...

2 comments
jnigh
jnigh

I've followed all the steps to decommission Exchange 2003 in a Org where 2007 has been installed. I'm concerned about the warning from Microsoft regarding deleting legacy Administrative Groups. One of the final steps in decommission is uninstalling Exchange 2003 from the last 2003 server. Can someone confirm that uninstalling via add/remove programs will not remove these legacy groups, as I suspect it won't? They would have to be manually deleted in ESM, right? I would appreciate someone who has done this to confirm. Thanks.

p.j.hutchison
p.j.hutchison

Yes, I believe you are correct, that removing the last server does NOT remove the Administrative Group. It will leave an empty group which can be left alone which may be the case for things like legacy Exchange DNs or the need to install Exchange 2003 again.