Glue is all you need, especially with a porous, non-oily wood like mahogany. As always, I recommend you put a coat of shellac on the outside of the miters to protect from squeeze-out. Then sand it off. Of course, amber shaellac you get at the Home Cemter makes a great finish for mahogany.
Who needs spell-check; I can still spell Martini. Mmmmm.