Outra forma de inicializar o Exchange Web Service

Exemplo em ASPX no Page_Load()

As Flags de AppSettings são valores que vêm do web.config, podes passa-las directamente alterando os valores no código

 

/// <summary>
/// Page Load Event.
/// </summary>
/// <param name="sender">Control Invoking this event.</param>
/// <param name="e">Event Arguments.</param>
protected void Page_Load(object sender, EventArgs e)
{
   //// Initialize EWS service.
   ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2010);
   service.Credentials = new WebCredentials(ConfigurationManager.AppSettings["EmailAddress"], 
        ConfigurationManager.AppSettings["Password"]);
   service.AutodiscoverUrl(ConfigurationManager.AppSettings["EmailAddress"], delegate(string url) { return true; });       
}