Do the math: Bush had taken 418 days of vacation in his first 6.7 years in office. That works out to 62.4 vacation days a year — a little more than 12 work weeks, which is probably slightly more vacation time than you get. On the other hand, think how much more damage Bush could have done if he hadn't taken so much vacation.
Anyway, multiply 62.4 days a year by eight and you get 499 total days of vacation.
Compare that with the 473 days of e-mail missing. All Bush's handlers have to do to keep pace is destroy 26 more days of e-mails. They can probably handle that.