namespace Exc18Email
{
    class Email
    {
        static void Main(string[] args)
        {
            string text = "Some text dd@yahoo.com more text santiago.vedra@ygmail.co.uk and test_mail@abv.bg";

            string[] array = text.Split(' ');

            foreach (var item in array)
            {
                if( item.Contains('@') == true)
                    Console.WriteLine(item);
            }
        }
    }
}