hi there i have a basic question but im confused can somebody explain please in brief the function of the followingMAILBOX role CAS role HT role edge transport role UC role plus i have a question , is it necessary to install CAS to access my mailbox ! ? isnt it enough to just install mailbox role ???thanks

Hi,I will try to explain what I am clear about your questions MAILBOX RoleThe Mailbox server role hosts mailbox databases, which contain users' mailboxes. If you plan to host user mailboxes, public folders, or both, the Mailbox server role is required.CAS Role The Client Access server role supports the Microsoft Outlook Web Access and Microsoft Exchange ActiveSync client applications and the Post Office Protocol version 3 (POP3) and Internet Message Access Protocol version 4rev1 (IMAP4) protocols. The Client Access server role also supports services, such as the Autodiscover service and Web services. The Client Access server role accepts connections to your Exchange 2007 server from a variety of different clients. Software clients such as Microsoft Outlook Express and Eudora use POP3 or IMAP4 connections to communicate with the Exchange server. Hardware clients, such as mobile devices, use ActiveSync, POP3, or IMAP4 to communicate with the Exchange server. The Client Access server role is required in every Exchange Server 2007 organization.HT Role Deployed inside your Active Directory directory service forest, the Hub Transport server role handles all mail flow inside the organization, applies transport rules, applies journaling policies, and delivers messages to a recipient's mailbox. Messages that are sent to the Internet are relayed by the Hub Transport server to the Edge Transport server role that is deployed in the perimeter network. Messages that are received from the Internet are processed by the Edge Transport server before they are relayed to the Hub Transport server. If you do not have an Edge Transport server, you can configure the Hub Transport server to relay Internet messages directly. You can also install and configure the Edge Transport server agents on the Hub Transport server to provide anti-spam and antivirus protection inside the organization.You must deploy a Hub Transport server role in each Active Directory site that contains a Mailbox server role.ET RoleIn Exchange 2007, the Edge Transport server role is deployed in your organization's perimeter network as a stand-alone server or as a member server of a perimeter-based Active Directory domain. Designed to minimize the attack surface, the Edge Transport server handles all Internet-facing mail flow, which provides Simple Mail Transfer Protocol (SMTP) relay and smart host services for the Exchange organization. Additional layers of message protection and security are provided by a series of agents that run on the Edge Transport server and act on messages as they are processed by the message transport components. These agents support the features that provide protection against viruses and spam and apply transport rules to control message flow. The computer that has the Edge Transport server role installed doesn't have access to the Active Directory directory service. UM RoleExchange Server 2007 Unified Messaging combines voice messaging, fax, and e-mail into one Inbox, which can be accessed from the telephone and the computer. Unified Messaging integrates Exchange Server 2007 with the telephony network in your organization and brings the features found in Unified Messaging to the core of the Exchange Server product line. Thsese explanations will help to solve your issues plus the clear answer to your additional question Regards from www.windowsadmin.info

manu thanks for the great explaination but i didnt have the answer for my additional question though :D i know its a MUSt to have it in my organization but my question is to access my mailbox using outlook 2007 ( ONLY ACCESSING IT ) does it need CAS ?i heard in exchange 2010 YES but in 2007 no ?correct me please if im wrong thanks

Hi, Exchange 2007's Client Access Server accepts connections from: Browser-based clients using either the full-featured Outlook Web Access (OWA) or a new OWA Light client Mobile devices via Exchange ActiveSync (EAS) Phone devices via Outlook by Phone POP3 or IMAP4 clients, such as Outlook Express and Eudora CAS also enables Microsoft Outlook 2007 clients to Autodiscover mailbox location from pretty much anywhere, as long as a CAS server is reachable. Essentially, a Microsoft Outlook 2007 client starts out looking at the email address of the user whose profile is being configured. Thus you must have a CAS server enabled in your infrastructure based on Exchange 2007.It is same as for 2010 also see here http://technet.microsoft.com/en-us/library/bb124915.aspx Regards from www.windowsadmin.info

ok thanks :)