Only sensible technical way I can see to do it would be an embedded link in the e-mail which leads to a summary page on the website. The users would have to click on the link to view the summary page. When you change the content on the summary page, the users see the changed contents. If you delete the page, the link then fails.
Actually embedding the data into the mail won't work: it just has to be the link to the data
However this presupposes that your users don't download or cache the webpage on their PCs. It also presupposes that you block robots from (e.g The Wayback Machine) from trawling the site....
However I'm with mixture on this. Its imperative that you get the legal side sorted out. If you intend to run a website which hosts other peoples copyrighted material then you are in for a world of legal pain
Last edited by Milo Minderbinder; 13th January 2013 at 21:30.