Automatically pass credentials of current user to ExchangeService object - - Microsoft Outlook 2013

Hi,

Using app for Office, we want to read the attachment of the email. We are able to read it using ExchangeService. Currently we are providing the specific UserName/Password in order to authenticate the ExchangeService.

ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2010_SP1);

service.Credentials = new WebCredentials("UserName", "password", "domain.contoso.com");

Say, if the user is already logged in to Outlook and already authenticated, can the same token be used instead of passing hard-coded information?