"For example: if the recipient never opens the links featured in the email, an email like "Are you still interested in this?" could be sent after some time..."

"For example: if the recipient never opens the links featured in the email, an email like "Are you still interested in this?" could be sent after some time..." Though that makes sense from the user's point of view, I don't think many mailing-list managers would go for that because it would decrease their memberships. The features I'm talking about are here to please the subscriber so that he doesn't unsubscribe :) But I agree that there could be even more complex options. One thing I thought of for certain types of mailing lists (e.g. HNSummaries could work): you can sign up for a delayed email that takes into account how the first receivers reacted to your links. Let's say the email is made of 25 hottest links from HN. You could then get a delayed email with only the 10 most clicked from these 25. Or one that automatically adapts to the kind of stories you've apparently found interesting.