Error javax.mail.AuthenticationFailedException: 535 5.7.8 Error: authentication failed: UGFzc3dvcmQ6 during trying to send an email

I would like to send an email, when someone will try order thing in my application. So I have created a two main method to do this. The first sender method set configurations for sender. There I set host, user data, port, and other settings.

@Configuration
public class EmailData {
    @Bean
    public JavaMailSender javaMailSender() {
        JavaMailSenderImpl javaMailSender = new JavaMailSenderImpl();
        javaMailSender.setHost("poczta.interia.pl");
        javaMailSender.setPort(587);
        javaMailSender.setUsername("myemail@interia.pl");
        javaMailSender.setPassword("adminadmin123");
        Properties properties = javaMailSender.getJavaMailProperties();
        properties.put("mail.transport.protocol", "smtp");
        properties.put("mail.smtp.auth", "false");
        properties.put("mail.smtp.starttls.enable", "true");
        properties.put("mail.debug", "true");
        return javaMailSender;
    }
}

And the second method in class service trying to send a message:

@Service
@Async
public class EmailService {

    @Autowired
    private JavaMailSender javaMailSender;

    public EmailService(JavaMailSender javaMailSender) {
        this.javaMailSender = javaMailSender;
    }

    public void sendMail(String toEmail, long idOrder) {

        SimpleMailMessage simpleMailMessage = new SimpleMailMessage();

        simpleMailMessage.setFrom("myemail@interia.pl");
        simpleMailMessage.setTo("myemail1@gmail.com");
        simpleMailMessage.setSubject("subject");
        simpleMailMessage.setText("Thanks for your order!");

        javaMailSender.send(simpleMailMessage);
}

There I am trying to send an email, but last line throws an exception:

javax.mail.AuthenticationFailedException: 535 5.7.8 Error: authentication failed: UGFzc3dvcmQ6

Also I have a configuration in properties file:

spring.mail.host=poczta.interia.pl
spring.mail.port=587
spring.mail.username=myemail@interia.pl
spring.mail.password=adminadmin123
spring.mail.properties.mail.smtp.auth=false
spring.mail.properties.mail.smtp.starttls.enable=true

What is wrong? Why it throws an error? It seems that email and password are correct. Any help will be appreciated.