Sending Mail to Contact's Old mail Id

trigger MailSend on Contact (after update) {      
    for(Contact con:trigger.new){
    Contact oldCon = Trigger.OldMap.get(con.ID);
        if(con.Email != oldcon.Email){          
            Messaging.SingleEmailMessage semail = new Messaging.SingleEmailMessage();
String[] sendingTo = new String[]{oldcon.Email};
semail.setToAddresses(sendingTo);
semail.setSubject('Single Email message Example');
semail.setPlainTextBody('Hello!!!!!!!!!!This is a test email to test single email message program');
Messaging.sendEmail(new Messaging.SingleEmailMessage[] {semail});                      
        }
    }
}