Windows Exchange Server users not receiving external ISP emails retrieved by POP3 connector.
When setting up a new server, with Microsoft Exchange Server, users will loose their external SMTP email, retrieved via the POP3 connector, until you go into recipient policies and change the include the smtp domain name as a address the server is responsible for eg @mpa.com.au
Until the above is done the POP3 Connector will be pulling down emails from the internet and they will just disappear as the server does not have a recipient policy to process the emails from this domain.
Also if a user matthew has an primary SMTP email address in exchange of matthew@myorg.com.au
and a pop3 connector is set up to retrieve email for matthew.smith@people.net.au to be delivered to matthew@myorg.com.au
The email will not arrive unless
1) matthew has a 2nd smtp email address of matthew.smith@myorg.com.au, and
2) you have a recipient policy for @people.net.au (leave unticked
This exchange server is responsible for all mail delivery to this address
3) USe the Global Mailbox and let exchange route the email to the individual user account.