Exchange 2010 FAQ: What are the Exchange Server 2010 Server Roles?Question: What are the new server roles for Exchange Server 2010 and how do they match up with Exchange Server 2003?

Exchange Server 2007 introduced a new roles-based server architecture that is continued with Exchange Server 2010.  An Exchange 2010 server is installed only with the roles you choose (with some limitations that I’ll go into shortly) instead of being installed with the entire Exchange Server 2010 product.

This approach means that Exchange 2010 servers are easier to configure, easier to secure, easier to maintain, and easier to size for hardware.

The server roles in Exchange Server 2010 are:

  • Mailbox Server – hosts the mailbox and public folder databases
  • Client Access Server – provides connectivity for clients (eg Outlook, Outlook Web App, ActiveSync) to mailboxes
  • Hub Transport Server – responsible for all mail flow in the organization
  • Edge Transport Server – a special transport server intended for installation in DMZ networks to provide secure inbound/outbound email flow for the organization
  • Unified Messaging Server – provides voice mail and other telephony integration with Exchange

So how do these roles match up with Exchange Server 2003?

  • The Mailbox server is basically the same as an Exchange 2003 server that hosts databases (though Exchange 2010 has very different high availability features)
  • The Client Access server is similar to an Exchange 2003 front-end server
  • The Hub Transport server is similar to an Exchange 2003 bridgehead server
  • The Edge Transport and Unified Messaging roles are new and don’t closely related to Exchange 2003

Exchange 2010 servers can be configured with multiple server roles.

  • Small environments often install a “Typical” Exchange 2010 server running the Mailbox, Client Access, and Hub Transport roles
  • Medium sized environments often install the Hub Transport and Client Access roles together, but separate from the Mailbox servers
  • Large organizations tend to separate servers into dedicated roles so they can scale appropriately
  • Unified Messaging is not all that common in my experience so far but will co-exist with the Mailbox, Hub Transport, or Client Access roles
  • Edge Transport servers can’t co-exist with any other server role

To read more about Exchange Server 2010 server roles on Microsoft TechNet click here.

About the Author

Paul Cunningham

Paul is a former Microsoft MVP for Office Apps and Services. He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. Paul no longer writes for


  1. Ipsita Bera

    what have you written my friend?

  2. santosh kumar

    Hii sir i m microsoft er so like this use for exchange server

  3. S品


  4. Gentry38


    I’m planning on adding another exchange that will hold mailbox for disabled accounts. Can I just install the mailbox role and not the other role? Or is the mailbox role dependent on hub or cas role?


  5. karthika

    can you let me know the consequence of having bot mailbox role and CAS rile installed in the same server?

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      Paul Cunningham

      It’s recommended to deploy multi-role servers, so there’s no negative consequences to mention here.

  6. Murtuza Bhabhrawala

    Hi Paul,

    Can you tell me what would be the best way for naive like me to perfectly understand Microsoft Exchange Server? I’m looking forward to make my career in this. Your advice would be appreciated.

    Thank you.

    1. Arjun den

      Hi Paul,

      I’m too eagerly waiting for your reply on this, a career in Ms Exchange Server!


      1. Avatar photo
        Paul Cunningham

        Take a training course or read a book and sit the certification exam. If you build your own lab for exam prep you’ll learn more than the average person knows. Beyond that it’s mostly experience and the ability to read documentation and test ideas to solve problems. Exchange is not something to focus exclusively on these days though, but it has so many related topics (AD, security, certs, servers/storage, the cloud) that it’s a good basis for a broader skill set.

  7. Mike

    Hello Paul, I need to migrate a Exchange 2007 to 2010, but one 2007 with UM will stay. Do you see any issues here? Thank you

    1. Avatar photo
      Paul Cunningham

      I don’t do much UM work but my assumption is that 2010 mailbox users who are enabled for UM will need a 2010 UM server.

      1. Mike

        Thanks Paul, that would make sense!

  8. Sheeraz Ali Zaidi


    Just need your expert advise. Currently we have around 4000 Mailbox with 4 boxes (2 HubCAS & 2 Mailbox Role) one of my team mate suggest to combined all three roles in one box and we are going to implement site resilience architecture as well.

    can you please suggest if doing so will be beneficial for us.

    Note: our existing system never have any downtime or glitch from day one. we are running since 3 years.

  9. Natesh

    Hi Pual,

    We in the process of consolidation of 2 office location. We have 1 FE and 2 MBX on each location.
    We are planning to move to new location. I would like to know the best practice to move the FE roles to the new location. Connectivity between the new location and the 1 of the existing location is to on P2P.

    Let me know if this approach works.

    Location A and B
    New location C

    Move all the Mailbox from location B to Location A, where I have the internet facing (FE) is currently located. Then, configure a New FE on the new location C. New location will have new set of VLAN and IP range.

    Question: What are the changes to made on the exchange FE?

    Many thanks in advance


  10. Vaughan Douglas


    We’re using Exchange 2010 SP3 in our small environment as a message archive (over IMAP). We deliberately excluded the Hub Transport because the server will not send/receive; it just accepts messages moved from our campus-wide Exchange. It works as we expected. However, Exchange logs many events errors looking for the Hub Transport. Are there any negative consequences (other than the logged events) to leaving the Hub Transport out of the Exchange environment configured as it is?


    1. Avatar photo
      Paul Cunningham

      I don’t know to be honest. You’re the first person I’ve heard of who is doing that.

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