How Exchange 2010 message routing works

Inbound

  1. Email get routed to external SMTP server ( such as Edge server, Barracuda, Postini etc.). This device scans for Virus/Spam and send it Exchange Hub Transport server.
  2. Hub Transport server scans the message against its rule/policy. If it matches, it takes action as specified in the rule. Once done, it forwards the message to mailbox server role where user resides.
  3. Mailbox server role process the mail and place it in user’s mailbox

Outbound

    • Users use Outlook, OWA or mobile device to send a message.
    • Mailbox server role delivers the message to Hub Transport role. It decides where to send the message to. If message is destined for a user in the organization, It sends it to recipient mailbox server.
    •  If message is destined to external user, it uses DNS to send it out to the internet.