Retrieve email ID of a recipient from mail client using asp.net
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I am working on a email marketing solution. In this application I am sending mass mail to 1000 recipient with a link attached to download a document. My question is how do i capture the email address of the recipient who have downloaded the attachment. I am able to track the Ip address of the recipient but I am not finding a way to capture the Email ID of the recipient who has downloaded the link.

It is very very urgent can some one help me

Thanks in advance      