Please how can do signature extraction from the email body by Text mining by c#

RequestSettings logininfo = new RequestSettings("",textBox1 .Text ,textBox2 .Text);
logininfo.AutoPaging = true;
ContactsRequest crequest=new ContactsRequest(logininfo) ;
Feed<contact> feedcontacts = crequest.GetContacts();
foreach (Contact gmailAddresses in feedcontacts.Entries)
{
   Console.WriteLine("\t" + gmailAddresses.Title);
   listBox1.Items.Add(gmailAddresses.Title);
   foreach (EMail emailId in gmailAddresses.Emails) 
   {
      Console.WriteLine("\t" + emailId.Address);
      listBox1.Items.Add(" " + emailId.Address);
   }
}