About Proxy Generation DLLs

Development of a Microsoft Exchange Server Gateway includes creation of a proxy generation DLL. The code in this DLL is able to create e-mail addresses for Exchange server recipient objects in the format that the foreign e-mail system understands. Such custom made e-mail addresses are called proxies. Proxy is just another name for an e-mail address string recognizable by a specific electronic messaging system.

Each recipient object in Microsoft Exchange Server has several e-mail addresses (proxies), one for each installed address type. You can review these addresses by using the "E-mail Addresses" tab on the recipient properties dialog. Notice that each proxy is prefixed by an address type such as SMTP, X400, etc. followed by a detailed electronic address. For example, when I reviewed two of my own e-mail addresses I had obtained the following:

SMTP:NikOkuntseff@WRConsulting.com
X400:c=US;a= ;p=WRConsulting;o=WhiteRock;s=Okuntseff;g=Nik;

Exchange Administrator in raw mode shows the "E-mail Addresses" attribute for each recipient object. This attribute is an array of strings. Each string is a proxy for one electronic messaging system. In the example above the top line is my Internet proxy address, and the bottom - my X.400 proxy address.

Proxy generation DLLs are modules that generate such custom e-mail strings for Exchange server recipients using its properties such as PR_DISPLAY_NAME and others. For example, when a new recipient (user) is added to the Exchange server site, e-mail addresses for all installed address types are generated automatically by these DLLs. If you install an additional address type XYZ, and a gateway that delivers to XYZ messaging system, then you must also create and install XYZ proxy generation DLL. This DLL should be able to create an XYZ address for each Exchange server recipient. This address is used when the XYZ system sends messages to Exchange using XYZ addressing format. Exchange server does an address lookup upon receiving of an XYZ message to decide which user is a recipient for the message.