This is the expected behaviour, as the solutions described only affect notifications, not the actual state of the service. You will still see the service in WARN/CRIT state, but you won’t get any notifications.
As far as i know there is no way to achieve what you have in mind, as checkmk always represents the actual state of things. The closest would be the answer on the first link you posted in your original answer.
If your “mail-bulks” always come at the same time you might be able to solve this issue with setting time-specific thresholds. You can define that at specific times the thresholds for the mail queue can be higher and e.g. 30 minutes after that it should be back to normal. But that would only work if you know at what time you receive the messages.