As we've talked about at length before, web-based email providers such as Gmail, Yahoo, and Hotmail, take into account the open rates and click-through rates associated with the email that you send to their users. If your rates are too low, they will start putting your email in the spam folder. But in addition to the obvious concerns and issues related to open rates, there is another aspect of these web-based mail providers - and Gmail in particular - to which nobody gives a thought, even though it is quietly killing email deliverability for countless legitimate, ethical email marketers and other email senders.