New mail notification icon in systray. There have been some discussions about this in the past, and I have read them. But nothing worked (at least not on Win 7 and eM Client 10.0.3530.
I do not know when I can switch to Win 10.
I would suggest to update to Windows 10 now and not delay, as “Windows 7 is no longer secure or supported anymore at Microsoft” so is risky using Windows 7 anymore. Windows 10 is still secure and supported till October 2025.
This mail notification issue you are having could be to do with eg: the latest eM Client is not designed for Windows 7 and the old OS may not have the support needed for the tray icon.
So best option is to upgrade to Windows 10 or Windows 11 If your hardware supports that and then see the following thread on how to enable mail notifications in the test for Win 10 & 11.