Generally every single exchange recipient object will have more than one proxy address with each foreign address type having one address. The addresses for every foreign address type are invented by a dynamic-link library known as DLL. The location of the DLL is specified as an attribute of the Address-Type object during the install of the address type in the Microsoft Active Directory.
Users can possess a primary or secondary address. The primary address for a user is used to send email to the unknown system while the secondary type is used when the unknown system send email to the users. The primary address is used on outdoing messages to be the address of the sender while the recipient listed in the message will be matched in the Active Directory according to the secondary proxy addresses to search for the ip address my accurate receiver on incoming messages. A user can have only one primary address but may possess numerous secondary addresses. For instance if two companies combine and provide new email addresses to their staffs, the secondary addresses can be used for employees to receive emails at both their new and old email addresses. As the old email addresses are remained as secondary addresses, the incoming emails can be addressed to either the new or old address. At the same time, outgoing email will always be addressed by the primary proxy address.
There should be a gateway to generate addresses for the following types of receiver objects: groups, contacts, public folders and users. The gateway need not generate addresses for only one-off address. To have a view on the address for exchange user, you can click on the “Email Addresses” tab on the property page in the Active Directory Users and Computers application. The application is situated under the node of Program Files or Administrative Tools in the Microsoft Windows server. You can easily create a proxy address manually via the user interface or you can take the automatic route using the proxy generation DLL. If the gateway serves an unknown messaging system that does not contain addresses in the Microsoft Exchange Server system then you will need to provide an associated proxy generation DLL and the Address-Type object.
The proxy generation DLL will carry out multiple functions that the exchange server required to create the addresses. When there is a new address installed, the proxy generation DLL related to the new foreign address type will be called to produce a unique and new proxy address for every user. After the new user is added, the proxy generation DLL for every address type will be notified to create addresses for the new user.