mail:
    host: smtp.gmail.com
    port: 587
    username: myuser@gmail.com
    password: mypass
    protocol: smtp
    tls: true
properties.mail.smtp:
    auth: true
    starttls.enable: true
    #ssl.trust: smtp.gmail.com
    starttls.required: true
jhipster:
mail: # specific JHipster mail property, for standard properties see MailProperties
    from: myuser@gmail.com
    base-url: http://127.0.0.1:8080

package com.pfg.easyschedule.service;

import com.pfg.easyschedule.domain.User;

import io.github.jhipster.config.JHipsterProperties;

import org.apache.commons.lang3.CharEncoding;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.autoconfigure.mail.MailProperties;
import org.springframework.context.MessageSource;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;
import org.thymeleaf.context.Context;
import org.thymeleaf.spring4.SpringTemplateEngine;

import javax.inject.Inject;
import javax.mail.internet.MimeMessage;
import java.util.Locale;
import java.util.Map;

/**
 * Service for sending e-mails.
 * <p>
 * We use the @Async annotation to send e-mails asynchronously.
 * </p>
 */
@Service
public class MailService {

    private final Logger log = LoggerFactory.getLogger(MailService.class);
    private static final String USER = "user";
    private static final String BASE_URL = "baseUrl";
    private final JHipsterProperties jHipsterProperties;
    private final JavaMailSender javaMailSender;
    private final MessageSource messageSource;
    private final SpringTemplateEngine templateEngine;


    public MailService(JHipsterProperties jHipsterProperties, JavaMailSender javaMailSender,
            MessageSource messageSource, SpringTemplateEngine templateEngine) {

        this.jHipsterProperties = jHipsterProperties;
        this.javaMailSender = javaMailSender;
        this.messageSource = messageSource;
        this.templateEngine = templateEngine;
    }

    @Async
    public void sendEmail(String to, String subject, String content, boolean isMultipart, boolean isHtml) {
        log.debug("Send e-mail[multipart '{}' and html '{}'] to '{}' with subject '{}' and content={}",
            isMultipart, isHtml, to, subject, content);

        // Prepare message using a Spring helper
        MimeMessage mimeMessage = javaMailSender.createMimeMessage();
        try {
            MimeMessageHelper message = new MimeMessageHelper(mimeMessage, isMultipart, CharEncoding.UTF_8);
            message.setTo(to);
            message.setFrom(jHipsterProperties.getMail().getFrom());
            message.setSubject(subject);
            message.setText(content, isHtml);
            javaMailSender.send(mimeMessage);
            log.debug("Sent e-mail to User '{}'", to);
        } catch (Exception e) {
            log.warn("E-mail could not be sent to user '{}'", to, e);
        }
    }

    @Async
    public void sendActivationEmail(User user) {
        log.debug("Sending activation e-mail to '{}'", user.getEmail());
        Locale locale = Locale.forLanguageTag(user.getLangKey());
        Context context = new Context(locale);
        context.setVariable(USER, user);
        context.setVariable(BASE_URL, jHipsterProperties.getMail().getBaseUrl());
        String content = templateEngine.process("activationEmail", context);
        String subject = messageSource.getMessage("email.activation.title", null, locale);
        sendEmail(user.getEmail(), subject, content, false, true);
    }

    @Async
    public void sendCreationEmail(User user) {
        log.debug("Sending creation e-mail to '{}'", user.getEmail());
        Locale locale = Locale.forLanguageTag(user.getLangKey());
        Context context = new Context(locale);
        context.setVariable(USER, user);
        context.setVariable(BASE_URL, jHipsterProperties.getMail().getBaseUrl());
        String content = templateEngine.process("creationEmail", context);
        String subject = messageSource.getMessage("email.activation.title", null, locale);
        sendEmail(user.getEmail(), subject, content, false, true);
    }

    @Async
    public void sendPasswordResetMail(User user) {
        log.debug("Sending password reset e-mail to '{}'", user.getEmail());
        Locale locale = Locale.forLanguageTag(user.getLangKey());
        Context context = new Context(locale);
        context.setVariable(USER, user);
        context.setVariable(BASE_URL, jHipsterProperties.getMail().getBaseUrl());
        String content = templateEngine.process("passwordResetEmail", context);
        String subject = messageSource.getMessage("email.reset.title", null, locale);
        sendEmail(user.getEmail(), subject, content, false, true);
    }
}

@RestController

private final Logger log =
LoggerFactory.getLogger(MyClassResource.class);

@Autowired
EntityManager entityManager;
@Autowired
MailService mailService;
@PostMapping ("/myurl")
@Timed
public ResponseEntity<Boolean> mymethod(@RequestBody myObject data) {
mailService.sendEmail(
            "emailTo@gmail.com",
            "message from spring",
            "hi world. this message is from spring",
            true,
            true
        );
}

c....MailService   : E-mail could not be sent to user 'emailTo@gmail.com'

org.springframework.mail.MailSendException: Failed messages: com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first. w125sm9354452wmb.45 - gsmtp

at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:474)
at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:345)
at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:340)
.........