In C#, fetch an Active Directory user's full name and email address given only their username. Pretty much just implemented this: http://stackoverflow.com/questions/785527/get-mail-address-from-activedirectory

Program.cs

using System;
using System.DirectoryServices;

namespace EmailAddressTest
{
    class Program
    {
        static void Main(string[] args)
        {
            do
            {
                Console.WriteLine();
                Console.WriteLine("------------------");
                String username = Environment.UserName;
                Console.WriteLine("Enter the username in question [leave blank for {0}]:", username);
                String newUsername = Console.ReadLine();
                if (!string.IsNullOrWhiteSpace(newUsername)) username = newUsername;

                // get a DirectorySearcher object
                var entry = new DirectoryEntry();
                var search = new DirectorySearcher(entry);

                // specify the search filter
                search.Filter = "(&(objectClass=user)(anr=" + username + "))";

                // specify which property values to return in the search
                search.PropertiesToLoad.Add("givenName"); // first name
                search.PropertiesToLoad.Add("sn"); // last name
                search.PropertiesToLoad.Add("mail"); // smtp mail address

                // perform the search
                SearchResult result = search.FindOne();
                if (result == null)
                {
                    Console.WriteLine("*** user {0} not found", username);
                }
                else
                {
                    Console.WriteLine("Name = {0} {1}", result.Properties["givenName"][0], result.Properties["sn"][0]);
                    Console.WriteLine("Email = {0}", result.Properties["mail"][0]);
                }
                Console.WriteLine("press 'y' to try again, any other key to exit.");
            } while (Console.ReadKey().KeyChar.ToString().ToLower() == "y");


        }
    }
}