email.send({
    author: senderId,
    recipients: recipientId,
    subject: 'Test Sample Email Module',
    body: 'email body',
    attachments: [fileObj],
    relatedRecords: {
           entityId: recipientId,
            customRecord:{
                  id:recordId,
                  recordType: recordTypeId //an integer value
                  }
      }
});

I’m trying to send an email and have it get recorded under the email tab of a custom record. I think I would just set that in the relatedRecords subobject, however

recordType: recordTypeId //an integer value

what would the integer value of recordType be?