sending emails to membership users.

Hi, i've seen how to send emails in asp.net using the class System.Net.Mail but now i need to know how to:
get the email address of the users in certains roles, for example, everything a new record in inserted , notify the admin user and a technician about that new record.
i have 4 roles, admin, technician, advisor, so i need to get their emails address in some way to send them a copy of that email. Any ideas would be appreciate it. 
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