I have a question about this answer
Ok... here goes...
Actually embed a 1x1 pixel and customise the html email when it is sent out to include the email address of the recipient in the querystring. ie <IMG SRC="http://firstname.lastname@example.org
then all you do is use a logging analysis app like Webtrends to filter out this image data and do some processing on the querystring and you have some loggin info on the mail you sent out.
You will need access to the web logs and you can probably get your host to add most of the fields you require.
Emails are sent as HTML email but the 1x1 pixel image actually isn't an image, but the SRC tag would actually refer to a page which logs all the enviroment variables on the pc which calls it.
eg <IMG SRC="http://email@example.com
Enviroment Variables are sent in the http header of every request and these can be accessed by the server that your tracking 'image' sits on. These Enviroment Variables can then be stored in your database and processed.
It's that simple!!
why would anyone use gif (method1) which is difficult for me to do,
when I can easily use (method2) webpage of asp with query string