Unable to send mail using email operator in AirFlow. Getting error [Errno 99] Cannot assign requested address. How to resolve this?

While I am using the Airflow Email Operator, I am facing an issue as shown, below.

I had made all the SMTP configurations and Gmail config too (setting up the 16-character password)

[2019-12-06 06:54:01,024] {{taskinstance.py:1047}} ERROR - [Errno 99] Cannot assign requested address

Can someone tell me what is this error and why it's not sending a mail?

The Code is

from datetime import datetime
from airflow import DAG
from airflow.operators.dummy_operator import DummyOperator
from airflow.operators.python_operator import PythonOperator
from airflow.operators.email_operator import EmailOperator

def print_hello():
    return 'Hello world!'

default_args = {
        'owner': 'peter',
        'start_date':datetime(2018,8,11),
}

dag = DAG('hello_world', description='Simple tutorial DAG',
          schedule_interval='* * * * *',
          default_args = default_args, catchup=False)

dummy_operator = DummyOperator(task_id='dummy_task', retries=3, dag=dag)

hello_operator = PythonOperator(task_id='hello_task', python_callable=print_hello, dag=dag)

email = EmailOperator(
        task_id='send_email',
        to='to@gmail.com',
        subject='Airflow Alert',
        html_content="""<h3>Email Test</h3> """,
        dag=dag
)

email >> dummy_operator >> hello_operator