using System;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;
public class Test
{
	public static void Main()
	{
		var s = "2.2|[johnnyappleseed@example.com]";
		var rx = new Regex(@"(?<=\[)[^]]+");
		Console.WriteLine(rx.Match(s).Value);
		
		var ss = s.Split('|');
		if (ss.GetLength(0) > 1)
		{
			var last = ss[ss.GetLength(0)-1];
			if (last.Contains("[") && last.Contains("@")) // We assume there is an email
				Console.WriteLine(last.Trim(new[] {'[', ']'}));
		}
	}
}