Are you just getting the username and doing a look up?
If that is the case you can go to Tools, Form options, and then Open and Save, and Rules. Here you can add this function and a data connection query and this will be executed as the form is opened and you can take action on the results before the default view is displayed.
We also have an Active Directory webservice which is included with our Database Accelerator package. Qdabra Database Accelerator Suite Version 2.1.2815 - Developer
With it you can get email address and other information. Also it works in VPN and RAS situations where the user may not be using a local domain account.