Way to communicate with Active Directory without providing credetials again n again to Directory Entry Object

hi,
i need to do the following
1. Authenticate from Active Directory
2. Get Email List of all users from active directory
I so have user credentials when system authenticates user...but later on when i need to get the list of email from active directory i dont have user credentials for creating Directory Entry. I dont want to store credetials in Sessionstate or something...and I dont want to use Admin Account...plz suggest some solution so that i can connect to active dierctory for getting other information after authentication.


Thanks

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