Mailing program

This program sends a newsletters to a specified list of clients

---

/Configs - contains the folowing configuration files:

• source_config.json - contains the sender's email:

{
    "email_sender": "login_example@gmail.com"
}

* it can be different email domains, not only @gmail.com

• secret_config.json - contains the sender's email password:

{
    "email_password": "password_example"
}

• clients.json - contains the clients email list:

{
    "clients_list": [
        "login_example@gmail.com",
        "login_example1@mail.ru"
    ]
}

TODO:

• to update message module (to add some additional logics)
• to build logging system