This question is not site specific, but--what happens behind the scenes which makes being removed from an email mailing list such a lengthy task? All websites which I've visited, if you wish to be added to a email mailing list, will do so instantly. But most of the time, if you wish to unsubscribe from a list, you land at a page saying something along the lines of 'you will be removed from the list within a week'. I can't figure out why it wouldn't be instant. Anyone know?
Also, if this is the wrong place to ask this question, can someone direct me to the right stack exchange site for this question?