Feature Request: Repeat the Sound until the MessageBox is closed

[Lisias]

Some emails are import (as alerts from the infra monitoring tool), and sometimes you are not in the computer when the alert email is received.

So I adjusted the Mailbox-Alert Message to linger on screen until I click on it.

Having the sound being repeated until the Message is dismissed would be useful, as it would help to detect the message when you are away from the computer.

A possible workaround is to create a long sound file, but then the #65 kicks in and so you have a annoying sound being played even after closing the Message.