Mailbox Verifier - Any New Mail Waiting?

Some time ago I told you about my plans to turn an empty old bottle of champagne into a new mail announcer. Whether or not these attempts will prove of avail, I had wondered what actually happens as air is blown across the opening of a bottle --- by whatever means, and for whatever reason.
When a jet of air is blown across (and slightly inside) the opening of a bottle's mound, it pushes down the air in the bottle a bit. The now compressed air acts like a spring and jumps back --- a wee too far, of course, which produces a light deficit of air inside the bottle. This, again, causes more air to be sucked into it, and a vibration begins that produces the often surprisingly low sound. The whole apparatus can be understood as a Helmholtz resonator.
Now, you can use a recording of some bottle music as your new mail notification sound in Mailbox Verifier, of course (you can even set a different sound for unseen mail). That's not a requirement, however, and no Helmholtz resonances are needed either:
›› Mailbox Verifier provides core mail checker functionality and many options. (Windows)