I searched for plugin which will send automatic post email to subscribers when I post on my Wordpress blog but I had no luck finding this kind of plugin.
Does any one know any plugin which can do this thing?
Subscribe2 does what you are looking for.
Subscribe2 provides a comprehensive subscription management and email notification system for WordPress blogs that sends email notifications to a list of subscribers when you publish new content to your blog.
Email Notifications can be sent on a per-post basis or periodically in a Digest email. Additionally, certain categories can be excluded from inclusion in the notification and posts can be excluded on an individual basis by setting a custom field.
The plugin also handles subscription requests allowing users to publicly subscribe (Public Subscribers) by submitting their email address in an easy to use form or to register with your blog (Registered Users) which enables greater flexibility over the email content for per-post notifications for the subscriber. Admins are given control over the presentation of the email notifications, can bulk manage subscriptions for users and manually send email notices to subscribers.
Screenshot of the plugin interface
Credits: Subscribe2 Wordpress Plugins Page