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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

- If C(starttls), the connection will try to upgrade to a secure SSL/TLS connection, before sending.
      If it is unable to do so it will fail.
    type: str
    choices: [ always, never, starttls, try ]
    default: try
    version_added: '2.3'
  timeout:
    description:
    - Sets the timeout in seconds for connection attempts.
    type: int
    default: 20
    version_added: '2.3'
'''
EXAMPLES = r'''
- name: Example playbook sending mail to root
  mail:
    subject: System {{ ansible_hostname }} has been successfully provisioned.
  delegate_to: localhost
- name: Sending an e-mail using Gmail SMTP servers
  mail:
    host: smtp.gmail.com
    port: 587
    username: username@gmail.com
    password: mysecret
    to: John Smith <john.smith@example.com>
    subject: Ansible-report
    body: System {{ ansible_hostname }} has been successfully provisioned.
  delegate_to: localhost
- name: Send e-mail to a bunch of users, attaching files
  mail: