using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

            string example = "CCILIMS CCILIMS [ccilims@snclavalin.com]";

        // LINQ Way 

        string foo = string.Concat(example.TakeWhile((c) => c != '['));     

        Console.WriteLine(example);

        Console.WriteLine(foo);

        // Old School

        int index = example.IndexOf('[');

        Console.WriteLine(index);

        string result = example.Substring(0, index);

        Console.WriteLine(result);

    }

}