InfoPath Dev

I currently have a form which has a field that captures who the "Requestor" is. The field shows simply, "Doe, John" I need to grab the WorkEmail from this so-called Requestor. How do I query a current field and convert that into a WorkEmail? I can easily put this into another text box... but how? I'm losing my mind trying to figure this out and I'm sure it's easy once I get the answer.

If you are storing the user's alias, you can call GetUserProfile by setting the queryfields in the secondary data source for this data connection.

Once the query fields are set, then query the data connection.

The GetUserProfiler return a repeating table in the secondary data source. This table will have all the users data.

Then it's just a matter of using rules to set the field in the main data source, since you'll have all sorts of user data in the secondary data source (email, name, department, etc.)