private static List GetAllEMailAddresses(string text)
{
    List result = new List();
    System.Text.RegularExpressions.MatchCollection regexMatchCollection =     
    System.Text.RegularExpressions.Regex.
    Matches(text, @"\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*");

    for (int i = 0; i < regexMatchCollection.Count; i++)
        if (!result.Contains(regexMatchCollection[i].Value))
            result.Add(regexMatchCollection[i].Value);
    return result;
}