how to pass parameter in tag's src

hello thanks in advance
 
i want to pass parameter in image tag's src.
i send an image in email, for email tracking but i want to pass parameter in image tag's src. it gives me error please help me...
//*************************************************************************
 message.Body = "<img  src='http://test.com/test1.aspx?imageID=defaultimg.jpg&custID= + System.DateTime.Now + &campID='32434'/>";
//*************************************************************************
 
please hel me please
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