Place it at the reveal in a retro desktop or inbox edit, just after the on-screen message appears. Follow it with the Windows XP Error Sound when the reply goes wrong, or end the scene with The End Meme Sound for a clean retro finish.
About this sound
This under-a-second voice clip says “You've got mail” in a calm, friendly tone, with no music or extra effects behind the words. It feels warm and instantly familiar, like a small cheerful announcement arriving out of nowhere, and it sparks a quick flash of early-internet nostalgia. The line became widely known as the incoming-email alert for AOL during the dial-up era.