Kostya, you know my attitude: if you don't implement that, I'll just set on fire yet another voodoo doll of you and will continue using the Aquamail I have (of course, cursing Kostya every time I encounter the problem
).
But in this case, your response seems to indicate that I haven't done a good explaining the use case. (I was doing that from the cell phone, and I prefer a regular keyboard.)
Turning off or switching the phone's network connection works too (e.g. WiFi <-> mobile).
So, please excuse me for trying to make sure you really understand the use case(s).
Situation: In case of a bad connectivity (could be a weak Wi-Fi when mobile network is unavailable or impractical, e.g. in case of international roaming, or a weak mobile signal and no Wi-Fi), I need some other app to use the network urgently (pull some urgent information from the network). While I am doing that (and, despite the nominal 3G/4G or WiFi, it can be painfully slow, think of a 28.8K modem on a noisy line, if you've had that experience), Aquamail starts its scheduled check, making that slow connection even worse.
That slows "the app of interest" to a crawl, or even can cause a timeout in the connection for that app.
A remedy in such a situation is to
quickly (before the timeout might occur) cancel Aquamail's sync.
I hope now it is clear why "turning off or switching the phone's network connection " is not an option
at all.
The easiest (and the quickest) way to cancel the sync qucikly would be to pull down the notifications from the top, and either swipe away the notification for the AM sync or to click a button on that notification (similar to the buttons appearing on the new message notifications).
The problem with the menu item is that it takes some time to get to it, especially when Aquamail hasn't been used recently, i.e. it might not be in the "short-list".
(And, just for the record, I didn't mean that that menu item should be made persistent. I mentioned it not being persistent just as an aside that it is hard to find it unless you know where it is.)
Besides, in one situation when it happens somewhat often, I'd be driving, and waiting for Waze or Google Maps to recalculate the directions. So, besides the time required for opening Aquamail and going to the menu, doing that while driving is not very practical. Add to that that the need for the urgent recalculation of direction is usually a result of a non-standard situation (highway closure), which is making the entire situation a bit more ... stressful, I guess.
In another situation, I'd be trying to obtain urgently some necessary information before the network connection disappears completely: before entering an area with no data connectivity (rural part of the country, long tunnel, before the aircraft takes off, etc.).
I hope this post clearly describes some of the situations where a quick and easy way to cancel the scheduled Aquamail sync would be a great benefit. But I understand if that still wouldn't make it a priority (see the first sentence above).