JavaMailのダウンロード
JavaMailはJAF(JavaBeans Activation Framework)に依存しているので
javamail1_4_7.zipとjaf-1_1_1.zipを以下のアドレスからダウンロード
2つともこのページからダウンロードできる
zipファイルを解凍して得られるmail.jarとactivation.jarをWebContent\WEB-INF\libにコピー
以下省略...
SendMail.java
package com.sample.simpleinquiry;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Properties;

import javax.mail.Message;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class SendInquiry
 */
@WebServlet("/SendMail")
public class SendMail extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public SendInquiry() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		
		request.setCharacterEncoding("UTF-8");
		
		String title = request.getParameter("title");
		String message = request.getParameter("message");
		
		//System.out.println("タイトル：" + title);
		//System.out.println("メッセージ" + message);
		
		response.setContentType("text/html; charset=UTF-8");
		
		PrintWriter out = response.getWriter();
		
		try{
			Properties property = new Properties();
			
			property.put("mail.smtp.host","smtp.gmail.com");
			
			//GmailのSMTPを使う場合
			property.put("mail.smtp.auth", "true");
			property.put("mail.smtp.starttls.enable", "true");
			property.put("mail.smtp.host", "smtp.gmail.com");
			property.put("mail.smtp.port", "587");
			property.put("mail.smtp.debug", "true");
			
	        Session session = Session.getInstance(property, new javax.mail.Authenticator(){
	            protected PasswordAuthentication getPasswordAuthentication(){
	                return new PasswordAuthentication("Gmailのユーザ名", "Gmailのパスワード");
	            }
	        });
	        
	        /*
	        //一般的なSMTPを使う場合
	        
			//ポートが25の場合は省略可能
			property.put("mail.smtp.port", 25);
			
			Session session = 
					Session.getDefaultInstance(property, null);
			*/
			
			MimeMessage mimeMessage = new MimeMessage(session);
			
			InternetAddress toAddress = 
					new InternetAddress("受信者のメールアドレス", "受信者の名前");
			
			mimeMessage.setRecipient(Message.RecipientType.TO, toAddress);
			
			InternetAddress fromAddress = 
					new InternetAddress("送信者のメールアドレス","送信者の名前");
			
			mimeMessage.setFrom(fromAddress);
			
			mimeMessage.setSubject(title, "ISO-2022-JP");
			
			mimeMessage.setText(message, "ISO-2022-JP");
			
			Transport.send(mimeMessage);
			
			out.println("<htm><body>");
			out.println("■お問い合わせ内容を担当者へ送信しました。");
			out.println("<body></html>");
		}
		catch(Exception e){
			out.println("<html><body>");
			out.println("■担当者への送信に失敗しました");
			out.println("<br>エラーの内容" + e);
			out.println("</body></html>");
		}
		
		out.close();
	}

}