public interface MailSender {

    /**
     * Send the given simple mail message.
     * @param simpleMessage message to send
     * @throws MailException in case of message, authentication, or send errors
     */
    public void send(SimpleMailMessage simpleMessage) throws MailException;

    /**
     * Send the given array of simple mail messages in batch.
     * @param simpleMessages messages to send
     * @throws MailException in case of message, authentication, or send errors
     */
    public void send(SimpleMailMessage[] simpleMessages) throws MailException;

}

public interface JavaMailSender extends MailSender {

    /**
     * Create a new JavaMail MimeMessage for the underlying JavaMail Session
     * of this sender. Needs to be called to create MimeMessage instances
     * that can be prepared by the client and passed to send(MimeMessage).
     * @return the new MimeMessage instance
     * @see #send(MimeMessage)
     * @see #send(MimeMessage[])
     */
    public MimeMessage createMimeMessage();

    /**
     * Send the given JavaMail MIME message.
     * The message needs to have been created with createMimeMessage.
     * @param mimeMessage message to send
     * @throws MailException in case of message, authentication, or send errors
     * @see #createMimeMessage
     */
    public void send(MimeMessage mimeMessage) throws MailException;

    /**
     * Send the given array of JavaMail MIME messages in batch.
     * The messages need to have been created with createMimeMessage.
     * @param mimeMessages messages to send
     * @throws MailException in case of message, authentication, or send errors
     * @see #createMimeMessage
     */
    public void send(MimeMessage[] mimeMessages) throws MailException;

    /**
     * Send the JavaMail MIME message prepared by the given MimeMessagePreparator.
     * Alternative way to prepare MimeMessage instances, instead of createMimeMessage
     * and send(MimeMessage) calls. Takes care of proper exception conversion.
     * @param mimeMessagePreparator the preparator to use
     * @throws MailException in case of message, authentication, or send errors
     */
    public void send(MimeMessagePreparator mimeMessagePreparator) throws MailException;

    /**
     * Send the JavaMail MIME messages prepared by the given MimeMessagePreparators.
     * Alternative way to prepare MimeMessage instances, instead of createMimeMessage
     * and send(MimeMessage[]) calls. Takes care of proper exception conversion.
     * @param mimeMessagePreparators the preparator to use
     * @throws MailException in case of message, authentication, or send errors
     */
    public void send(MimeMessagePreparator[] mimeMessagePreparators) throws MailException;

}

public interface MimeMessagePreparator {

    /**
     * Prepare the given new MimeMessage instance.
     * @param mimeMessage the message to prepare
     * @throws MessagingException passing any exceptions thrown by MimeMessage
     * methods through for automatic conversion to the MailException hierarchy
     */
    void prepare(MimeMessage mimeMessage) throws MessagingException;

}

public interface OrderManager {

    void placeOrder(Order order);
}

import org.springframework.mail.MailException;
import org.springframework.mail.MailSender;
import org.springframework.mail.SimpleMailMessage;

public class OrderManagerImpl implements OrderManager {

    private MailSender mailSender;
    private SimpleMailMessage message;

    public void setMailSender(MailSender mailSender) {
        this.mailSender = mailSender;
    }

    public void setMessage(SimpleMailMessage message) {
        this.message = message;
    }

    public void placeOrder(Order order) {

        //... * Do the business calculations....
        //... * Call the collaborators to persist the order

        //Create a thread safe "sandbox" of the message
        SimpleMailMessage msg = new SimpleMailMessage(this.message);
        msg.setTo(order.getCustomer().getEmailAddress());
        msg.setText(
            "Dear "
                + order.getCustomer().getFirstName()
                + order.getCustomer().getLastName()
                + ", thank you for placing order. Your order number is "
                + order.getOrderNumber());
        try{
            mailSender.send(msg);
        }
        catch(MailException ex) {
            //log it and go on
            System.err.println(ex.getMessage());            
        }
    }
}

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

import javax.mail.internet.MimeMessage;
import org.springframework.mail.MailException;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessagePreparator;

public class OrderManagerImpl implements OrderManager {
    private JavaMailSender mailSender;
    
    public void setMailSender(JavaMailSender mailSender) {
        this.mailSender = mailSender;
    }

    public void placeOrder(final Order order) {

        //... * Do the business calculations....
        //... * Call the collaborators to persist the order
        
        
        MimeMessagePreparator preparator = new MimeMessagePreparator() {
            public void prepare(MimeMessage mimeMessage) throws MessagingException {
                mimeMessage.setRecipient(Message.RecipientType.TO, 
                        new InternetAddress(order.getCustomer().getEmailAddress()));
                mimeMessage.setFrom(new InternetAddress("mail@mycompany.com"));
                mimeMessage.setText(
                    "Dear "
                        + order.getCustomer().getFirstName()
                        + order.getCustomer().getLastName()
                        + ", thank you for placing order. Your order number is "
                        + order.getOrderNumber());
            }
        };
        try{
            mailSender.send(preparator);
        }
        catch(MailException ex) {
            //log it and go on
            System.err.println(ex.getMessage());            
        }
    }
}