Sendgrid Inbound Parse webhook and Java MimeMessage Compatibility

Question

I am trying to parse raw mime message which sengrid post to a URL by inbound parse web hook settings. Previously i was listening for incoming mails from Mailserver through Imap and from java MimeMessage i was able to convert it to the String and vice versa. Please see below code how i used to convert from MimeMessage to String and vice versa in java.

private void convertMimeMessageToStringAndViceVersa(javax.mail.internet.MimeMessage message) {

        ByteArrayOutputStream bStream = new ByteArrayOutputStream();
        message.writeTo(bStream);
        String rawMimeMessageString = new String(bStream.toByteArray(), StandardCharsets.UTF_8.name());

        // Now from the above String to MimeMessage see below code
        
        Properties props = new Properties();
        Session session = Session.getDefaultInstance(props, null);
        ByteArrayInputStream bais = new ByteArrayInputStream(rawMimeMessageString.getBytes());
        javax.mail.internet.MimeMessage convertedMimeMessage = new MimeMessage(session, bais);
        
}

So my question is, i cannot convert the string raw mail message which sendgrid is posting through inbound parse webhook to javax.mail.internet.MimeMessage type. Is there anyway.

Answer 1

Probably SendGrid Raw MimeMessage is broken, however you can try to use non-raw payload and convert this payload to whatever you want.

According to this article: https://varunsastrydevulapalli.medium.com/the-sendgrid-inbound-webhook-with-spring-dc7b5bae4e0c, we can receive the Inbound Message using this spring controller:

@Controller
@RequestMapping(value = "/messaging")
public class InboundMessageController {
@Bean(name = "multipartResolver")
 public CommonsMultipartResolver commonsMultipartResolver() {
 CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();
 commonsMultipartResolver.setDefaultEncoding("UTF-8");
 commonsMultipartResolver.setMaxUploadSize(5000);
 return commonsMultipartResolver;
 }
 
 @RequestMapping(value = "/inbound", method = {RequestMethod.POST, RequestMethod.HEAD}, consumes = MediaType.MULTIPART_FORM_DATA)
 public @ResponseBody
 void processInboundSendGridEmails(HttpServletRequest request,
 HttpServletResponse response,
 @RequestParam(required = false) MultipartFile file,
 SendGridInbound sendGridInbound) {
  System.out.println(sendGridInbound);
  convertToMimeMessage(sendGridInbound);
 }
}

public class SendGridInbound {
    String headers;
    String dkim;
    String to;
    String html;
    String from;
    String text;
    String sender_ip;
    String spam_report;
    String envelope;
    String attachments;
    String subject;
    String spam_score;
    String attchmentInfo;
    String charsets;
    String spf;

    //getter setters toString
}

Hope it could help.

Answer 2

The previous solution hasn't worked to me. But the following solution worked fine. This code snippet reads the request through the class MimeMessage, to learn how to deal with that you can read this topic.

Here goes the solution:

package package_;

import org.apache.log4j.Logger;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.internet.MimeMessage;
import javax.servlet.http.HttpServletRequest;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

@RestController
@RequestMapping("/listener")
public class SendGridListener {

    protected final Logger logger = Logger.getLogger(this.getClass());

    @RequestMapping(
            method = {RequestMethod.POST},
            consumes = {MediaType.MULTIPART_FORM_DATA_VALUE}
    )

    public @ResponseBody void listen(HttpServletRequest request) throws MessagingException, IOException {
        String email = request.getParameter("email");
        Session s = Session.getInstance(new Properties());
        InputStream is = new ByteArrayInputStream(email.getBytes());
        MimeMessage message = new MimeMessage(s, is);
        logger.info(message);
    }
}