title: Pass Email list as an argument from other dag in airflow
body: <p>I have created a custom email alert python file, I am calling that function in another dag to send email.
  Lets say - email alert file is <strong><code>custom_alert.py</code></strong></p>
  <pre><code>from airflow.operators.email import EmailOperator
  from airflow.utils.email import send_email
  
  def custom_failure_email(context, **kwargs):
      &quot;&quot;&quot;Send custom email alerts.&quot;&quot;&quot;
      dag_run = context.get('task_instance').dag_id
      subject = f&quot;[ActionReq]-dag failure-{dag_run}&quot;
      # email contents
      body= &quot;&quot;&quot;Hi Team,&lt;br&gt;&lt;br&gt;
              &lt;b style=&quot;font-size:15px;color:red;&quot;&gt;Airflow job on error, please find details below.&lt;/b&gt;
              Thank you!,&lt;br&gt;
              )
      email_list = ['aditya.dhanraj@gmail.com', 'something@gmail.com']
      for i in range(len(email_list)):
          send_email(str(email_list[i]),subject,body)
  </code></pre>
  <p>In Parent DAG : Lets Say <code>**email.py**</code> - I am calling the above function to send failure email.</p>
  <pre><code>from custom_alert import custom_failure_email
  default_args = {
      'owner': 'airflow',
      'depends_on_past': False,
      'email': ['noreply@gmail.com'],
      'email_on_failure': False,
      'on_failure_callback': custom_failure_email}
  </code></pre>
  <p>This way I am able to send the custom email, but my recipient list is same for every dag.
  Please let me know, How I can customize it to send different recipient email address for different dag. <strong>How I can pass recipient email address from Parent Dag.</strong>?</p>