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##### SUMMARY
mail module does not send email with Date header. It should send email with "Date" header automatically without any manual email header manipulation.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
mail

##### ANSIBLE VERSION
```
ansible 2.8.1
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/yclee/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/dist-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.15+ (default, Nov 27 2018, 23:36:35) [GCC 7.3.0]
```

##### CONFIGURATION
(None)

##### OS / ENVIRONMENT
Ubuntu 18.04

##### STEPS TO REPRODUCE
N/A

##### EXPECTED RESULTS
email should have Date headers

##### ACTUAL RESULTS
email did not  have Date headers and I have to manually insert it

from __future__ import absolute_import, division, print_function
__metaclass__ = type
ANSIBLE_METADATA = {'metadata_version': '1.1',
                    'status': ['stableinterface'],
                    'supported_by': 'community'}
DOCUMENTATION = r'''
---
author:
- Dag Wieers (@dagwieers)
module: mail
short_description: Send an email
description:
- This module is useful for sending emails from playbooks.
- One may wonder why automate sending emails?  In complex environments
  there are from time to time processes that cannot be automated, either
  because you lack the authority to make it so, or because not everyone
  agrees to a common approach.
- If you cannot automate a specific step, but the step is non-blocking,
  sending out an email to the responsible party to make them perform their
  part of the bargain is an elegant way to put the responsibility in
  someone else's lap.
- Of course sending out a mail can be equally useful as a way to notify
  one or more people in a team that a specific action has been