Sendgrid-nodejs: How to create a message thread w/ mail api

Created on 30 May 2018 · 3Comments · Source: sendgrid/sendgrid-nodejs

Issue Summary

I have a webhook setup for parsing inbound emails, which works fine, but I'm using the mail api to reply to the sender of that email. I can send the email just fine, but I want to reply to the senders email and build an email thread. I couldn't find anything on this topic in Sendgrid's docs other than the ability to add custom headers.

After looking into how emails work in general, I learned about the In-Reply-To field and the References field. I successfully pulled the Message-ID from the sender's email and I set the In-Reply-To field to it in my messages header. On top of this, I append the Message-ID to the References string and send that along as well.

When I look at the raw email in Gmail, I can see that both fields are set, but it still sends as a new email rather than a reply to the original.

This is basically my code, I can't show everything, but if anything needs clarifying, I'll be more than willing to do so.

  const msg = {
    to: from,
    headers: {
      References: `${references} ${messageId}`,
      'In-Reply-To': messageId
    },
    from: '[email protected]',
    subject: 'subject',
    text: 'reply',
  };

  sgMail.send(msg)

As far as the References field goes, I'm just taking the previous references from the sender's email and then appending the Message-ID to it. I have a feeling I might not be doing this right but I'm not totally sure.

Thanks for the help!

Best Regards,
Chris

question

Source

Chrischuck

Most helpful comment

It turns out in order to make a reply, you need to have to sender's email subject in your email's subject.

  const msg = {
    to: from,
    headers: {
      References: `${references} ${messageId}`,
      'In-Reply-To': messageId
    },
    from: '[email protected]',
    subject: `Re: ${subject}`, // where subject is the sender's subject.
    text: 'reply'
  };

Chrischuck on 31 May 2018

🎉14

All 3 comments

It turns out in order to make a reply, you need to have to sender's email subject in your email's subject.

  const msg = {
    to: from,
    headers: {
      References: `${references} ${messageId}`,
      'In-Reply-To': messageId
    },
    from: '[email protected]',
    subject: `Re: ${subject}`, // where subject is the sender's subject.
    text: 'reply'
  };

Chrischuck on 31 May 2018

🎉14

Thanks for providing the solution @Chrischuck!