I might have asked this question in the past but want more confirmation.
The flow of email in Exchange 2003/2007 & 2010
in Exchange 2003
Reading email from exchange server: Outlook connects to Exchange server and reads email
when sending from internal to external, it goes straight to internet without going through Front End server
External email : if it's coming through OWA, outlook mobile phone, blackberry ( user has an account in the exchange server), then it should go through Front end server to back end server.
if it s coming from public emails such as Hotmail or Yahoo then it goes straight to exchange server without going through front end server.
BUT , I have seen environments that don't have Front End Exchange server , just the Back End-- so what is the pros and cons of having FE or not having it.
in Exhcange 2007 & Exchange 2010
Internal email : when viewing email , Outlook connects to Exchange Mailbox server role and view the emails without going through Client Access .
when sending internal email to internal email address, outlook sends an email straight to Exchange Mailbox role server without going through Client Access role
when sending internal email to external email, the email goes from the Mailbox to the HUB and to the EDGE then to internet, [without passing through Client Acces]
External email: if it 's sent through OWA, outlook mobile phone, blackberry ( user has an account in the exchange server) the email comes through EDGE to HUB to Client Access server then to Mailbox server.
if it's sent through Yahoo, Hotmail then it comes through EDGE to HUB to Mailbox server without passing through Client Access.
***CLIENT ACCESS ROLE is kind of confusing , any Exchange2007/2010 expert to clear this confusion up?