Java로 메일 전송하기

SMTP 서버 설정정보로 세션을 흭득하고
MimeMessage에 세션을 가지고 메시지를 만들고
Transport 로 메시지를 전송한다.

세션을 만들때 default세션으로 가져오면 다른 계정에 대한 정보를 인지하지 않고 기본세션정보만 가져오기 때문에 유의해야한다.

import org.springframework.util.StringUtils;

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class MailSender {
    private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(MailSender.class);
    private final String account;
    private final String fromEmail;
    private final List<String> toEmails;
    private final String subject;
    private final String content;
    private final List<String> failMails = new ArrayList<>();
    private final String regex = "^[_a-z0-9-]+(.[_a-z0-9-]+)*@(?:\\w+\\.)+\\w+$";
    private final Pattern emailAddressPattern = Pattern.compile(regex);
    private final String password;
    private int sendSuccessCount;
    private String errorMessage;

    public MailSender(String account, String password, String fromEmail, List<String> toEmails, String subject, String content) {
        this.account = account;
        this.fromEmail = fromEmail;
        this.toEmails = toEmails;
        this.subject = subject;
        this.content = content;
        this.password = password;
    }

    public List<String> getFailMails() {
        return failMails;
    }

    public int getSendSuccessCount() {
        return sendSuccessCount;
    }

    public int getTotalToMails() {
        return toEmails.size();
    }

    public InternetAddress createEmailAddress(String mailAddressString, String person, String encoding) {
        try {
            return new InternetAddress(mailAddressString, person, encoding);
        } catch (Exception e) {
            failMails.add(mailAddressString);
            return null;
        }
    }

    public InternetAddress createEmailAddress(String mailAddressString) {
        try {
            return new InternetAddress(mailAddressString);
        } catch (Exception e) {
            failMails.add(mailAddressString);
            return null;
        }
    }

    public List<InternetAddress> createEmailAddresses(List<String> mailAddressStrings) {
        List<InternetAddress> mails = new ArrayList<>(mailAddressStrings.size());
        for (String mailAddressString : mailAddressStrings) {
            Matcher m = emailAddressPattern.matcher(mailAddressString);
            if (!m.matches()) {
                failMails.add(mailAddressString);
                continue;
            }
            InternetAddress emailAddress = createEmailAddress(mailAddressString);
            if (emailAddress != null)
                mails.add(emailAddress);
        }
        return mails;
    }

    public void sendMail() {
        Properties props = new Properties();

        //네이버 웍스 메일 서버
        props.put("mail.smtp.host", "smtp.worksmobile.com");
        props.put("mail.smtp.port", "465");
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.ssl.enable", "true");
        props.put("mail.smtp.ssl.trust", "smtp.worksmobile.com");
        props.put("mail.smtp.ssl.protocols", "TLSv1.2");

        Message msg;
        try {
            Session session = getSession(props);
            log.info(session.toString());
            msg = new MimeMessage(session);
        } catch (Exception e) {
            errorMessage = e.getMessage();
            return;
        }

        if (!StringUtils.hasText(content)) {
            errorMessage = "내용이 없음";
            return;
        }

        InternetAddress fromEmailAddress = createEmailAddress(account, fromEmail, "utf-8");
        if (fromEmailAddress == null) {
            errorMessage = "송신자 주소가 없음";
            return;
        }

        List<InternetAddress> emailAddresses = createEmailAddresses(toEmails);
        try {
            msg.setFrom(fromEmailAddress);
            msg.setRecipients(Message.RecipientType.TO, emailAddresses.toArray(new InternetAddress[0]));
            msg.setSentDate(new Date());
            msg.setSubject(subject);

            msg.setContent(content, "text/html;charset=utf-8");

            Transport.send(msg);
        } catch (MessagingException e) {
            errorMessage = e.getMessage();
            return;
        }
        sendSuccessCount = emailAddresses.size();
    }

    public String getErrorMessage() {
        return errorMessage;
    }

    private Session getSession(Properties props) {
        // 삽질한 부분. 기본 세션을 가져오면 계정을 암만 바꿔도 같은 계정으로만 가져온다.
        return Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(account, password);
            }
        });
    }

    public void failSendMail(String message) {
        this.errorMessage = message;
    }
}