Hi, I have a customer who considers to move one of there Exchange sites to Office365. Today they have 2 sites, the main site that runs Exchange 2010 with and casArray configured. In the other site, also an own ad site, runs Exchange 2003. Here we want to create another E2010 Casarray for the users and run a hybrid configuration with Office 365 to which we will migrate the users for this site. Can this be done at all? UC

i see no problem with this, but in most cases organization will move all their users to the Office365. Anyway i think your consideration is how to route the email between on-primes Exchange 2010 and Office 365 for Enterprises so note the following: Mail routing with a shared domain namespace between on-primes exchange and office 365 The on-premises organization can control mail flow for the on-premises and office 365 accounts single OWA URL can be used for both the on-premises and office 365 accounts also note that the office 365 forums is separated from the Exchange server forums if you will need assistant is your setup http://community.office365.com/en-us/f/default.aspx