Airflow - how to make EmailOperator html_content dynamic? : <p>I'm looking for a method that will allow the content of the emails sent by a given EmailOperator task to be set dynamically.  Ideally I would like to make the email contents dependent on the results of an xcom call, preferably through the html_content argument.</p>

<pre><code>alert = EmailOperator(
    task_id=alertTaskID,
    to='please@dontreply.com',
    subject='Airflow processing report',
    html_content='raw content #2',
    dag=dag
)
</code></pre>

<p>I notice that the Airflow docs say that xcom calls can be embedded in templates.  Perhaps there is a way to formulate an xcom pull using a template on a specified task ID then pass the result in as html_content?  Thanks</p>
