Mail Check Interval - missed? delay?

[Chuck99]

Gmail
Mail check interval = Custom
Custom check interval = 1 minutes
Message notifications = Enable


IMAP options
Enable optimizations = Uncheck


Account options
scheduled sync = check
Include in "Sync All' = check
IMAP Push = Uncheck


I have been using the above settings from Android 4.4; 5.1  Everything worked great. If people send me email, I will get notification within 1 minute. Both Wifi and Data work perfect.

This month, I just changed to Moto G (4th Gen.) Android 6 Marshmallow.
org.kman.AquaMail
Battery optimization = not optimized

Everything else are same as above.


Here is the problem:
Sometimes I get notification within 1 minute.
Most of the time, I get notification 7 to 15 minutes late after people sent me email. On both Wifi and Data.
I don't know if this has something to do with Android 6 Marshmallow?
I need help. My job is required me to see new email as soon as it arrives.

[nica]

Hi, what about enabling IMAP Push for the inbox folder? And setting for sync to 15 min?

You would get new mails immediately. Additionally it uses less battery power.

I don't know the reason for the issue you encountered, but it might be hard for client and server (risk of failure?), if sync of all folder every minute is expected.

Maybe Kostya can tell more or better.

[Kostya Vasilyev]

Yes, Android 6 has this thing called Doze Mode which limits the ability of apps to work in the background.

Even when an app is "whitelisted", periodic background tasks are still throttled -- can not occur more than once every 15 minutes or so.