# Subject not being set when using SendGrid dynamic templates

Sending via `@sendgrid/mail` with a dynamic transactional template: `subject: 'Test Subject'` in the message object plus `templateId` and `dynamic_template_data` does not set the email subject. The template's subject field in the SendGrid UI is empty. Sending without a template works fine.

## How to handle it

With dynamic transactional templates, the `subject` property of the send request is ignored; the subject comes from the template's own subject field. Fix: in the SendGrid template editor, set the subject line to `{{subject}}`, then pass the subject inside `dynamic_template_data`:

```js
const msg = {
  to: '[EMAIL]',
  from: '[EMAIL]',
  templateId: 'd-xxx',
  dynamic_template_data: { test_name: 'Testing Name', subject: 'Hello World' },
};
```
Multiple reporters confirmed this solves it.
Source: https://github.com/sendgrid/sendgrid-nodejs/issues/843