I'd get clear confirmation by contacting the licensing team http://www.microsoft.com/licensing/existing-customers/activation-centers.aspxSukh

Dear All I need your advice in order to buy the right license version of the following exchange 2010 deployment I need archiving solutions, I do not need more than 5 databases for each MBX boxes, so do I need Enterprise server and CAL license to be available to use archiving? Or I cna just get STD server abd enterprise CAL in order to use archiving? In the case that I should acquire Enterprise license for server MBX , do I need enterprise for CAS, HUB servers or I can mix ? Thanks in advance

I'd get clear confirmation by contacting the licensing team http://www.microsoft.com/licensing/existing-customers/activation-centers.aspxSukh

Like Sukh said, get clarification, but from my experience in licensing exchange 2010, for your requirements, you only need Exchange 2010 Standard, but add Enterprise CAL for every user you want to use advanced features on (Archiving, UM, etc..) ** The Enterprise CAL is an Add-on to the Standard CAL. All mailboxes require a Standard CAL ** If you were going to to go over the 5 Database limit of Exchange 2010 Standard, it is acceptable to purchase Exchange 2010 Enterprise for just the mailbox role servers and leave the Edge/HT/CAS as Standard. Here is the licensing link:http://www.microsoft.com/exchange/en-us/licensing-exchange-server-email.aspx

By the way, if you want to upgrade from Exchange Standard to Enterprise edition one day, you just need to enter a valid product key. If you want to deploy DAG, please make sure Windows Server 2008 is Enterprise edition.Frank Wang TechNet Community Support