java開發郵件發送（匿名)

環境：jdk8,maven
須要的pom，高版本發送會驗證spf，這個不會
如今發送郵件的FROM的域名必須和發送郵件的app在同一地址

<dependency>
            <groupId>javax.mail</groupId>
            <artifactId>javax.mail-api</artifactId>
            <version>1.5.6</version>
        </dependency>

純文本郵件內容發送

public class MailUtil {
    private final static String FROM = "**@**.com";

    public static void main(String[] args) {

        String mail ="***@**.com";
        String smtp = getSmtpByEmail(mail);
        Properties props = new Properties();
        props.put("mail.transport.protocol", "smtp");
        props.put("mail.smtp.host", smtp);
        props.put("mai.smtp.auth", "false");

        Session session = Session.getInstance(props, null);
        MimeMessage msg= new MimeMessage(session);
        try {
            msg.setFrom(FROM);
            msg.setSubject("緊急通知","gb2312");
            Multipart multipart = new MimeMultipart();
            MimeBodyPart bodyPart = new MimeBodyPart();
            bodyPart.setText("你的餘額已不足", "gb2312");
            multipart.addBodyPart(bodyPart);
            msg.setContent(multipart);
            msg.addHeader("X-Mailer", "Microsoft Outlook Express 6.00.2900.2869");
            msg.setRecipient(MimeMessage.RecipientType.TO,new InternetAddress(mail));
            Transport.send(msg);
            System.out.println("send success");
        } catch (MessagingException e) {
            e.printStackTrace();
        }
    }

    private static String getSmtpByEmail(String mail){
        Hashtable<String, String> hashtable = new Hashtable<>();
        hashtable.put(Context.PROVIDER_URL, "dns://");
        hashtable.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");

        String domain = mail.substring(mail.lastIndexOf('@') + 1);
        Attributes attrs = null;
        String smtp=null;
        try {
            InitialDirContext dirContext = new InitialDirContext(hashtable);
            attrs = dirContext.getAttributes(domain, new String[]{"MX"});
            NamingEnumeration<? extends Attribute> attrsAll = attrs.getAll();

            while(attrsAll.hasMore()) {
                Attribute next = attrsAll.next();
                for(int i=0;i<next.size();i++) {
                    String s = (String) next.get(i);
                    smtp = (s).substring(s.lastIndexOf(' ')+1);
                    break;
                }
            }
        } catch (NamingException e) {
            e.printStackTrace();
        }
        return smtp;

    }
}