trigger accouncustomertype on Account (before insert,after update) {

    accountcustomer.email_send(Trigger.new);

}

public class accountcustomer {

    public static void email_send( list<Account> acclist)
    {

        List<Messaging.SingleEmailMessage > Email_list=new List<Messaging.SingleEmailMessage >();
        for(Account Acc:acclist)
        {
            if(Acc.Type=='Customer')
                {
                        //op.addError('public class  accountcustomer{
    public static void email_send(list<Account> acclist)
    {

        List<Messaging.SingleEmailMessage > Email_list=new List<Messaging.SingleEmailMessage >();
        for(Account Acc:acclist)
        {
            if(Acc.Type=='Customer')
                {
                        //op.addError('');
                    System.debug('email send');
                Messaging.SingleEmailMessage message = new Messaging.SingleEmailMessage();
                 message.toAddresses =new String[] {'rajasekhara.bhavanam@forsysinc.com','rajarede08@gmail.com'};
                message.setSubject('Email test');
                String Body_data='';
                Body_data=Acc.Name;
                Body_data=Acc.Type;
                message.sethtmlBody(Body_data);
                Email_list.add(message);
                Messaging.sendEmail(new Messaging.SingleEmailMessage[] {message });
                }
        }


    }
}