I have set Mail to check for new items every 30 minutes. Never had a problem.
Since a short time the mail window opens up (meaning it is visible on the Desktop) at random moments. Independent whether or not there are new mails.
The moment of opening is not related to the intervalcheck. It completely happens at random. It's a bit irritating so I would like to prevent this.
But how?
I'm retired so there are very few entries in iCal, And I always only use notification thru popup window.
If setting up the system fully from scratch would not be such an horrid task then I would have done that already. Yet I fear that it will be th only way.
Try resetting the SMC. It does to tend to remove unexplained glitches.
Already tried that a few times, but no luck. It has started during El Capitan and hopen that updating to Sierra would help. No luck either.
I believe the latest Sierra is 10.12.6.
Try changing mail to the Manual check option and see if that makes a difference.
Changing makes no difference.
I'm wondering if this may be related to any alerts you have set up in Ical.
Mail window opens suddenly
