Exchange Server email not being sent externally through the SMTP server
Email sent to users of the local Active Directory domain (i.e., firstname.lastname@example.org) remains local and is stored automatically in the respective user's mailbox, but isn't sent externally via the SMTP server. Therefore, those users that aren't set up for Exchange Server in Microsoft Outlook (those retrieving email through conventional POP3 at our external mail server) do not receive the email.
How can I make it so all email sent is passed via the SMTP server and sent externally all the time? Conversely, how can I make it work for specific users?
This was first published in May 2007