Kostya, I encountered something in Aquamail behavior that might benefit from some improvement.
When Aquamail cannot sync mail with the server, in a while, it starts issuing notifications about that ("Persistent incoming server errors"). And those notifications are accompanied by [optional] vibration. (I don't remember if it was the default setting or not.) That's great. However, the problem is that it continues doing it after the initial notification.
So, I just had an episode when the server was unreachable large part of the day and overnight. So, the phone kept buzzing (vibrating) every 15 minutes.
Yes, I know about the problem and I cannot do anything until the server is back up. But I don't want to switch the notification off because otherwise I'll forget to turn it back on.
I'd think it would make sense that if there is an uncleared notification, the subsequent notifications for the same account(s) do not produce the vibration.
That can be either done as an option (IIRC, there is a similar option for message notifications: don't create a new one if the previous one is not cleared), or as an additional "choice" in the notification: "do not generate (or mute) subsequent notifications until this one is cleared".
I understand, it is not a frequent situation, - so most people do not get in such a situation. So, it is only when it happens, you realize what would be better...