While I was learning how to use django-registration app, I discover in the tutorial that I need to know how to send an email for the user to activate the registration.
我找到了这个指南，教我学习如何去使用 django-registration app，如何为用户发送电子邮件，以激活注册。
Thanks to folk at the Django chatroom, they advice me to google 'django gmail' and I discover a post at nathanostgard.com that show roughly how to do it. Here I'm going to extend a little on how to test it using shell.

1. Create a project, 创建一个项目

2. Edit settings.py with code below: 在settings.py 中添加如下代码

3. Run interactive mode, 运行交互模式

4. Import the EmailMessage module, 导入EmailMessage模块
    
5. Send the email, 发送邮件测试


Hope it help someone :) Reference here and here.
希望能帮助别人， :)  参考资料： here and here.