A Very Good Explanation of Regular Expressions

http://www.radsoftware.com.au/articles/regexlearnsyntax.aspx

C# Regular Expressions Cheat Sheet

http://www.mikesdotnetting.com/Article/46/CSharp-Regular-Expressions-Cheat-Sheet

Read PDF File

http://jadn.co.uk/w/ReadPdfUsingCsharp.htm

How to Find All Email Address in a Text File

using System.Text.RegularExpressions;
using System.IO;

string FileData = File.ReadAllText(fileName);

Regex emailregex = new Regex("(?<user>[^@]+)@(?<host>.+)");
MatchCollection matches = emailregex .Matches(FileData);
foreach (Match match in matches)
{
      Console.WriteLine(match.Value.ToString());
}