User synchronisation If you have Microsoft Exchange server, Mail essentials installed a User synchronisation agent. This agent retrieves the most up to date list of users from Exchange 5.5/2000. To do this, it requires an Exchange administrator account, which you specified during installation. This information is used to logon to Exchange server and retrieve the latest list of users. The User Synchronization options If you need to change these settings at any point, you can do this from the User synchronisation node in the Mail essentials configuration.