Now Blogger have provide this subscription gadget simply. How to add Follow by Email gadget? Just log in to your Blogger account, click Design. On Page Elements, add new gadget and choose Follow by Email gadget. This gadget provide a simple way for readers to subscribe which are delivered directly to email.
Once you add the Follow by Email gadget, readers visiting your blog can then just enter their email address and click Submit. Recent update of your blog delivered to visitor email automatically.