今天遇到这个问题折腾了好久，试了各种方法都没有，最后发现犯了一个很低级的错误：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.stereotype.Component;

import javax.mail.internet.MimeMessage;

@Component
public  class EmailSend {

    @Autowired
    private  JavaMailSender javaMailSender;

    private  String from = "*******@qq.com";

    private  String subject = "邮件";
    //正文
    private  String context = "验证码是:";

    public  void sendMail(String to,String code) {

        try {
            MimeMessage message = javaMailSender.createMimeMessage();
            //设置添加多部件multipart
            MimeMessageHelper helper = new MimeMessageHelper(message,true);
            helper.setFrom(from+"(宇宙超级无敌暴龙兽)");
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(context+code,true);
            javaMailSender.send(message);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

没错，就是这个署名from后的宇宙超级无敌暴龙兽 忘记加括号了！

把括号加上就好：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.stereotype.Component;

import javax.mail.internet.MimeMessage;

@Component
public  class EmailSend {

    @Autowired
    private  JavaMailSender javaMailSender;

    private  String from = "******@qq.com";

    private  String subject = "邮件";
    //正文
    private  String context = "验证码是:";

    public  void sendMail(String to,String code) {

        try {
            MimeMessage message = javaMailSender.createMimeMessage();
            //设置添加多部件multipart
            MimeMessageHelper helper = new MimeMessageHelper(message,true);
            helper.setFrom(from+"(宇宙超级无敌暴龙兽)");
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(context+code,true);
            javaMailSender.send(message);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

一开始我还以为是邮箱服务提供商有内容校验功能，“宇宙超级无敌暴龙兽”触发敏感词。。。。