On this website you can discover an array of historical salutations. When you found a matching ending for your e-mail you can easily copy it by clicking on the “quote me!”-button and then paste it at the end of your e-mail. If you don’t like the displayed salutation just click on “New Greeting” and you get another one that might fit the bill. To help you finding the fitting quote you can use the filter function.
old school video games (just search ‘do a barrel roll’), but you might not think the practice would catch on in the stuffy ranks of academia. Though not exactly widespread, academics have been known to amuse themselves by discreetly burying little jokes in their journal papers.