Duhigg, author of The Power of Habit, has an entire chapter dedicated to the power of small wins in his book. He says that small wins form a habit and our minds go back continually to where we were rewarded, and what better habit is there to establish for your new subscriber than to open your emails? If you want people to open your emails down the road, start by rewarding them with small victories. Train your audience to make a connection between your emails and making progress, and you’re in for much larger open rates in all of your future emails.
Let's look at an example. A Web email client might use Ajax to download the user's address book for autocompletion. If the user hasn't modified her address book since the last time she used the email web app, the previous address book response could be read from cache if that Ajax response was made cacheable with a future Expires or Cache-Control header. The browser must be informed when to use a previously cached address book response versus requesting a new one. This could be done by adding a timestamp to the address book Ajax URL indicating the last time the user modified her address book, for example, &t=1190241612 . If the address book hasn't been modified since the last download, the timestamp will be the same and the address book will be read from the browser's cache eliminating an extra HTTP roundtrip. If the user has modified her address book, the timestamp ensures the new URL doesn't match the cached response, and the browser will request the updated address book entries.
You are a man of culture, I love hearing of your whisky exploits and it is a shame to lose a lego collection.
The ideas here are spot on and I think the subdomains are often recognized like an entirely different domain. What we often refer to as domains aren't top level, com is a TLD not so the authority of com obviously doesn't flow into or if it does it only does so to a negligible degree. Since is a subdomain of com then wouldn't inherit authority either, it would be ranked all on its own and would be likely not to inherit penalties.