Email sent to users of the local Active Directory domain (i.e., [email protected]
) 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?
I can't tell from your question what version of Exchange Server you're running. As an example, if you're on Exchange Server 5.5, you can use the RerouteViaStore registry setting as described in Microsoft Knowledge Base Article 238471 XIMS:
How to force SMTP messages through the information store
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Related information from SearchExchange.com:
Tip: A primer on SMTP, POP and IMAP
Tip: Configuring Exchange Server to receive email from an ISP mailbox
Reference Center: SMTP tips and resources