How to make Android automatically check for new Gmail emails more frequently and notify it with a sound?

I'm going to make another attempt to find a solution to this. This has been the bane of my life, all the time without interruption, since I bought my first "smart" phone in 2012. I've always had an Android. My current phone is a Samsung J6 dual-sim, so quite old. But a few years ago it was relatively new: in fact I may have bought it on the recommendation that upgrading might solve the problem. No. Just today a client sent me an email and there was no notification for at least 4 hours. All the settings relating to Gmail are COMPLETELY correct. When I then sent myself an email to that address, yup, the notification sounded within less than a minute. The client in question was sending an email from France to me (in the UK). I struggle to believe this could be significant in 2025, but don't rule anything out. But it happens again and again and again. Over those 13 years I have lost 000s of £ due to clients sending me an email (always Gmail) and me not receiving the notification in a timely manner. By "timely" I mean maybe within 30 minutes. Though why notifications shouldn't be received as fast as the emails themselves I have always failed to understand. I have tried turning off battery optimisation and many, many other things. If you have a solution, please don't assume that a setting on your phone exists on my phone: it may, it may not. I believe (not entirely sure) that the gmail ICON does in fact appear in the top left of the phone: i.e. the problem seems to be that the acoustic signal (notification) of an arrived email often does not sound, or sounds only very belatedly. For unknown reasons. I'm a coder and am now inclined to see if I can develop an app, an extremely simple app, which, every minute or so, does a check to see whether this particular Gmail account has an email sitting there waiting to be read, and then MAKES A SOUND. I have never coded for Android and assume it would be quite annoying to develop this. If this is a possible solution surely someone must already have come up with something like it. There is a Reddit question on this theme from 2 years ago. One answerer replies as follows: > Android Gmail isn’t “checking” emails but is the Google Firebase Cloud Messaging pushing notifications to the device. That process should be instant, however for battery saving reasons Google (which made FCM as part of Google Mobile Services on your phone) decide to delay the display of some notifications including Gmail, on my device Gmail notifications are delayed until I unlock it. The solution will be using a local email client and keep that app open, or use another cloud based email client that pulls email to their server then use FCM to push to your phone, which less likely to cause delay. It seems that this person's first language is probably not English, and I'm having difficulty understanding either the suggested technical problem or the suggested solution. If someone here believes this holds a possible key, please try and explain it to me: "a local email client": what might that mean? And could "battery saving reasons" still be the culprit even if I have the optimisation completely turned off (which I do)? Any suggestions welcome. ***Later*** A couple of days of testing has in fact left me more frustrated than ever ... I simply don't understand. On my phone (Samsung J6 dual-sim) I now have no fewer than 3 alternative email apps (in addition to Gmail): BlueMail, Thunderbird and K-9. About 30 minutes ago I sent myself an email from another account (yahoo.co.uk) to my Gmail account (i.e. the one I use for my clients, where I want to get a sound notification every time a new email arrives). THE ONLY app which actually sounded was Gmail. Neither Bluemail, Thunderbird nor K-9 made any sound at all... and no notification icon is showing other than the Gmail one. In THEORY, Bluemail is set to "pull" ("fetch") emails every 3 minutes, and Thunderbird and K-9 are set to pull every 15 minutes. NONE of these apps is working at all. Over the past couple of days, as I've been testing things, I've occasionally had the sound notification from Thunderbird. Hardly ever from Bluemail. What could possibly explain these infuriating (apparent) failures of these apps to do what they're intended to do?