How to create a distribution list for sending eMail? In my project I want to create distribution list.
eg: while sending mail if I select drupal, then all drupal user should get mail. This means according to user group, mail will get created and if I selected any of the user group, then all mail id of that particular group will get selected and mail will send.

Any suggestions?
You can use the Rules module for this, simply by using Rules Action "Send mail to all users of a role". So all you'd have to do is to create a role that corresponds to your "user group", and grant access to the role you created for it.

However, if your user group consists of many, many users, then you might want to use a more granular approach as details in my answer to "How to delay sending emails using Rules to avoid being considered as a spammer?".