How to make a sound notification of an order for a delivery site?

Question

Yandex

The people here the question arose, at the moment a food delivery site has been made on opencart. After placing an order, the restaurant receives a letter to yandex mail stating that the order has been received. And here a problem arises, notifications that a letter has arrived in the mail, the first is not so noticeable (the yandex browser is used), moreover, it disappears very quickly, and the second sound is extremely quiet and not noticeable. The question is what can be done about it. Maybe there is a service, or plugins that will allow the sound notification to be more noticeable and longer, and for example, so that the information about the arrival of the letter is not removed after a few seconds? Maybe there are separate services where you can forward these letters? In general, tell me what you can.