When idle, only send email notification if status doesn't change to online in 1 minute
I suggest the following behavior when email notifications are turned on. Assuming email notifications are turned on, when a notification is triggered (direct message, mention, etc.), if the recipient's status is idle, trigger the usual MatterMost interface and system notifications, but wait 1 minute before generating an email. If the user's status changes back to online, we can assume they can/have seen the notification so do not generate an email. If their status is still away after the 1 minute delay, send the email as normal.
There are many times I have the MM client open but not the active window, so it marks me as idle. When a direct message or mention comes in, I see the notification, but as I am responding I also get an email about it, which is overkill.
There was another person requesting this in the past, but it was incorrectly marked as a duplicate of https://mattermost.atlassian.net/browse/PLT-2451, which has to do with email batching. I am not worried about the number/frequency of emails, but rather I am saying there not be any email in this case.