The site proxy address is the portion of a proxy address that corresponds to the site rather than to an individual user. For example, @trager.com might be the SMTP site proxy address for the Trager company. The site proxy address is treated as a separate entity to make it easier to create new proxy addresses in a case where, for example, a company changes its e-mail address. In such a situation, you would need to change only the site proxy address and then regenerate proxy addresses for all users at the company.