A new internet service has just been announced that gives free internet for a year if agree to receive an email advertisement every $30$ seconds while online. In other words, if you were online for $5$ minutes, $10$ email ads would show up in your email inbox during that time then you'd have to go into your inbox, open the ads, and delete them. While you were opening and deleting them, you'd still be online $,$ so more ads would come in$($To verify that you're living to your end of the bargain $,$ a return receipt is sent when you open an ad that works only when the computer is still online $,$ so you must remain online while opening and deleting ads $)$