sending php page by mail

Hi all, Description of my problem: i want to sent a newsletter to a mailgroup. However i also want to be able to see who read the mail at a certain moment and who didn't. Therefor i thought putting the page online, i.e. it's a php page which gets its data from the database. By sending a mail to the client with it's personal emailID, i can track who reads the mail when accessing the php page. That part works fine, but my problem now is that i want the page to be opened directly in the mail, so the receiver of the mail does not have to click on a link to see it.. Someone told me to use this: $msg_body = "<img src='http://www.domain.com/eletters/letters.php?ID=" . $letterID . "&emailID=" . $sendtoID . "'>"; But all i get, working like this is a broken image in the mail. This is the headers i use sending the mail: $headers .= "From: "; $headers .= "$mailfrom"; $headers .= "\nReply-To: "; $headers .= "$mailfrom"; $headers .= "\nMIME-Version: 1.0\nContent-Type: text/html; charset=iso-8859-1\n"; Did i forgot something? Is there an other way to do this? Thank you very much for any answer! See ya, Max