Under Client Access server (%BRAND_OUTLOOK_SHORT% Web App) , select %BRAND_OUTLOOK_SHORT% Web App is on the Intranet and ...

Under Client Access server (%BRAND_OUTLOOK_SHORT% Web App), select %BRAND_OUTLOOK_SHORT% Web App is on the Intranet and specify the internal FQDN of the %BRAND_EXCHANGE_ONLINE_SHORT% 2010 SP3 server that has the Client Access server role installed. For example, Ex2010.corp.contoso.com. Then select %BRAND_OUTLOOK_SHORT% Web App is on the Internet and specify the external FQDN of this server. For example, mail.contoso.com.