Mailbox Server Role
It contain content items like mailboxes, public folders, address list, resource schedules and meeting items. Database availability groups support the mailbox server; this support allows admins to deploy highly available mailboxes within the organization.
Client Access Server Role
The CAS role handles all connection between all external clients that need email access. All the protocols necessary for client access are handled in the CAS, including POP3, Internet Message Access Protocol 4 (IMAP4), Messaging Application Programming Interface (MAPI) and HTTPS. The CAS also supports Microsoft Outlook, Outlook Anywhere, Outlook Web App (OWA) and Exchange ActiveSync (EAS).
Hub Transport Server Role
This role processes, routes and delivers all mails sent through Exchange 2010. The hub transport server oversees message filtering and formatting and checks the validity of attachments. The hub transport roles also records and journals email messages. The server role can work in conjunction with an edge transport server role.
Edge Transport Server Role
It contain content items like mailboxes, public folders, address list, resource schedules and meeting items. Database availability groups support the mailbox server; this support allows admins to deploy highly available mailboxes within the organization.
Client Access Server Role
The CAS role handles all connection between all external clients that need email access. All the protocols necessary for client access are handled in the CAS, including POP3, Internet Message Access Protocol 4 (IMAP4), Messaging Application Programming Interface (MAPI) and HTTPS. The CAS also supports Microsoft Outlook, Outlook Anywhere, Outlook Web App (OWA) and Exchange ActiveSync (EAS).
Hub Transport Server Role
This role processes, routes and delivers all mails sent through Exchange 2010. The hub transport server oversees message filtering and formatting and checks the validity of attachments. The hub transport roles also records and journals email messages. The server role can work in conjunction with an edge transport server role.
Edge Transport Server Role
When installed this optional server role provides an added layer of security between the Exchange server 2010 organization and the outside network.The edge transport server checks that messages sent from outside an organization are free from spam and viruses before routing them to the hub transport server. Outgoing mail from the hub transport server is routed to the edge transport (if deployed) before leaving the Exchange organization.
Unified Messaging Server Role
The UM server, which is also optional, integrates an organization's PBX system with Exchange Server 2010. This stores business data like voicemail and faxes with email, calendars and contacts in users' mailboxes. Users also get features like call answering, automated greetings, message recording and fax support.
