You want to use security  Groups but mail enable them. Individual users
of that group  will still be able to get alert emails and emails like
that. The security group is just how they are authorized.

But is there any way to Progarammatically access security  group's Users
details like email id and other things
in sharepoint List. because i want to refer this groups  email ID's
In Sharepoint in _site database Userinfo table such information is available
but fro security groups users  Sharepoint will not import the users under
this group.

any Solution???

You cannot access information about members of a Security Group from inside of
SharePoint. What are you trying to do with their email addresses? Maybe
there's another way to get there.

I am Developing Workflow in sharepoint and my approver is available in this
groups (Department level approver group)
so for approving the documents i want to send email to individual approver
tha'ts i why i require email id for each user  under this group.

since security  group is having only one email id i can use this but this
will send mail to everybody in this group.
i don't want this,. so i want to extract each user email id .

any suggesstion how to handle  this situation?