exchange 2003 exchange 2010 during migration if you install hub and cas can you still have exchange 2003 recieve and send mail


  • Hi kind of new to exchange 2010

    im doing a migration of exchange 2003 to exchange 2010.

    My question is Do i have to install the CAS and Hub together for my outlook 2010 clients to stay connected to my exchange 2003.

    and if I do install the hub can exchange 2003 still handle mail flow from and to the internet...

    currently we only accept mail from postini which does our virus and spam filtering.....

    if I do not make any changes in DNS will anything change with the introduction of exchange 2010 hub and cas role.....

    I attempted to just install the CAS server with the following dns entries. to  FE exch03   . to exch2010 cas to exch201 cas

    some reason all my outlook client could no longer connect to my exch03 server....

    does this require the hub to be install as well..???

    thanks in advance experts...

    Thursday, March 29, 2012 3:54 PM

All replies

  • Have you installed all the prerequisites?  If you have done that your users should be able to access both 2003 and 2010 which ever holds their mailbox.

    Try below link for good info.

    Good luck!



    Thursday, March 29, 2012 5:27 PM
  • yes i did all the prerequisites, preparead, exbpa, server 2008 prep...

    when i install the CAS there was no error......owa was redirecting to

    only when i enable the and did my outlook2010 client freeze up..after a force close they could not connect to my exchange 2010 server??

    should outlook be offline when these changes are i have to manually configure outlook again??


    Thursday, March 29, 2012 6:31 PM
  • mogulsurf,

    Ex2010 won't come into play until you will migrate box(s) over to your 2010 mailstore. As long as you are not  resolving your production namespace to the CAS server everything will be processed by 03 as usual.

    If you did point your production name space to CAS you would have to configure redirect to 2003 for legacy boxes.

    Outlook 2003 doesn't utilize autodiscover. That function is build into Outlook 2007/2010. Like i mentioned before that would come into play once you will migrate boxes to 2010 mailstore.

    Friday, March 30, 2012 1:31 AM
  • hello Halo

    all my outlook clients are on 2010. will introducing the autodiscover dns cause them to disconnect from exhcnage 2003?

    when i install the CAS I only made one entry in the DNS ( and that went to my EX2003 FE server.

    that did  not cause any issues...

    later when i made the dns entry autodiscover and mail both pointing to my Exch2010 server is when my clients loss connection...

    all the mailboxes are on exchnage 2003

    our production name space is configure:    mx record   (exch03be)

                                                              host record   (exch03be)

                                                                mx record     (exch03FE)

                                                                host record   (exch03FE)

                                                               host record   (exch2010)

                                                                     alias  record       (exch03 FE)

    new entries                                       alias record (exch2010)

                                                                            alias record (exch2010)



    Friday, March 30, 2012 10:46 AM
  • do you have mailboxes that are 2010 mailstore?
    Saturday, March 31, 2012 2:58 AM
  • Hi,

    Exchange 2003 user will connect to mailbox server directly.

    What is the error when client try to connect to Exchange Server? Which client that you use to test? Owa? Outlook?

    What is the URL that you use to access OWA?

    Besides, I recommend you to enable IIS logging.

    Please do NSlookup from the below website and then post the result here.

    Xiu Zhang

    TechNet Community Support

    Monday, April 02, 2012 7:49 AM
  • Any update?

    Xiu Zhang

    TechNet Community Support

    Monday, April 09, 2012 2:50 AM